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Average
1. Five years ago, the average age of P and Q was 15 years. Average age of F, Q andR today is 20 years. How old will R be after 10 years?. [Bank P.O. 1989]
35 yrs 30 yrs
40 yrs 50 yrs
Answer & Explanation
Answer: 30 yrs
Explanation: (P + Q), five years ago = (15 * 2) = 30 years.
(P+Q), now = (30+5*2)years=40years.
(P + Q + R), now = (20 x 3) years =60 years.
R, now = (60 - 40) years = 20 years.
R, after 10 years = (20 + 10) years =30 years.
2. The average of Kanchans marks in 7 subjects is 75. His average in six subjects excluding Science is 72. How many marks did he get in Science? . [Bank P.O., 1993]
72 93
90 100
Answer & Explanation
Answer: 93
Explanation: Marks in Science (7*75 - 6-72) = 93.
3. The average age of 30 students of a class is 12 years. The average age of a group of 5 of the students is 10 years and that of another gfoup of 5 of them is 14 years. What is the average age oi the remaining students?.[Bank P.O. 1990]
8 years 12 years
10 years 14 years
Answer & Explanation
Answer: 12 years
Explanation: Total age of 20 students = (30 * 12) - (5*10 + 5*14)= 240 years.
Required average = (240/20) = 12 years.
4. Mukesh has twice as much money as Sohan and Sohan has 50% more money than what Pankaj has. If the average money with them is Rs 110, then Mukesh has :. [Assistant Grade]
Rs 55 Rs 90
Rs 60 Rs 180
Answer & Explanation
Answer: Rs 180
Explanation: Let pankaj has Rs x
then sohan has 150% of Rs x = 150x/100 = Rs 3x/2
mukesh has 3x ⇒ x + (3x/2) + 3x = 110*3 ⇒ 11x/2 =110*3 ⇒ x= 60
mukesh has Rs 180
5. A man whose bowling average is 12.4, takes 5 wickets for 26 runs and ther eby decreases his average by 0.4. The number of wickets, taken by him before his last match is :. [C.B.I. 1991]
85 72
78 64
Answer & Explanation
Answer: 85
Explanation: Let the number of wickets taken before the last match is x.
Then, (l2.4x + 26)/(x + 5) = 12 ⇒ l2.4x+26=12x+60
⇒ 0.4x=34 ⇒ x = 34/0.4 = 85
6. The average of first five multiples of 3 is:. [I.Tax and Cent]
3 8
6 9
Answer & Explanation
Answer: 9
Explanation: average = (1 + 2 + 3 + 4 + 5) * 3/5 = 15 * 3 / 5 = 9
7. The average age of 40 student of a class is 15 year. When 10 new students are admitted, the average is increased by 0.2 years. The average age of new students is :. [AssistaDt Grade]
15.2 yrs 16.2 yrs
16 yrs 16.4 yrs
Answer & Explanation
Answer: 16 yrs
Explanation: Sum of ages of 10 new students = (50*15.2 - 40*15) = 160 years
. Average age of new students = 160/10 = 16 years.
8. There are three sections of a class in a school. The number of students in the three sections is 38, 32 and 40 and the average age of the students in these sections separately is 15.3 years, 16.5 years and 15.9 years respectively. What is the average age of the class?. [Hotel Managemen]
15.9 yrs 15.96 yrs
15.92 yrs 15.86 yrs
Answer & Explanation
Answer: 15.86 yrs
Explanation: average = (38*15.3 + 32*16.5 + 40*15.9)/(38+32+40) = 1745.4/110 = 15.867
9. The average age of 30 students is 9 years. If the age of their teacher is included, it becomeS 10 years. The age of the teacher (in years)is :. [Assistant Grade]
27 35
31 40
Answer & Explanation
Answer: 40
Explanation: Age of the teacher = (31*10 + 30*9) = 40 years.
10. A motorist travels to a place 150 km away at an average speed of 50 km per hour and returns at 30 km per hour. His average speed for the whole journey in km per hour is :. [Bank P.O. 1991]
35 37.5
37 40
Answer & Explanation
Answer: 37.5
Explanation: Average speed = 2xy/(x + y) km/hr = 2*50*30/(50 + 30) = 37.5 km/hr
1. The average age of boys in the class is twice the number of girls in the class. If the ratio of boys and girls in the class of 36 be 5 : 1, what is the total of the ages (in years) of the boys in the class. [Bank P.O. 1989]
490 420
196 360
Answer & Explanation
Answer: 360
Explanation: Number of boys = 136 *(5/2) = 30,
Number of girls 6.
Average age of boys = (2 * 6) = 12 years.
Total age of boys (30 * 12) years = 360 years.
12. The mean of 1², 2², 3², 4², 5², 6², 7² is:. [U.D.C. Exam 199]
40 30
20 10
Answer & Explanation
Answer: 20
Explanation: sum of square of first n numbers n(n + 1)(2n + 1)/6
⇒ 7(7 + 1)(7*2 + 1)/6 = 140
average = 140/7 = 20
13. The mean of 100 observations was calculated as 40. It was found later on that one of the observations was misread as 83 instead of 53. The correct mean is :. [C.B.I. 1993]
39 40.3
39.7 42.7
Answer & Explanation
Answer: 39.7
Explanation: Correct sum = (40*100 + 53 - 83) = 3970.
Correct mean = 3970/100 = 39.7
14. The average age of a class is 15.8 years. The average age of the boys in the class is 16.4 yrs while that of the girls is 15.4 years. What is the ratio of boys to girls in the class? . [Hotel Managemen]
1:2 3:5
3:4 2 : 3
Answer & Explanation
Answer: 2 : 3
Explanation: Let the ratio is k : 1 . Then, k*16.4 + 1 * 15.4=(k+l)*15.8
or(16.4 - 15.8)k=(15.8-15.4) or k=0.4/0.6= 2/3.
Required ratio = 2/3 : 1 = 2 : 3
15. A team of 8 persons joins in a shooting competition. The best marksman scored 85 points. If he had scored 92 points; the average score for the team would have been 84. The number of points, the team scored, was :.[C.B.I. 1993]
672 645
665 588
Answer & Explanation
Answer: 665
Explanation: Let the total score be x.
(x +92 - 85)/8 = 84 so x+7 = 672 so x=665
16. The average of eight numbers is 14. The average of six of these numbers is 16. The average of the remaining two numbers is: . [Bank P.O. 1994]
4 16
8 Data inadequate
Answer & Explanation
Answer: 8
Explanation: Total sum of remaining two (8*14 - 6*16) = 16.
Average oLthese two numbers = 16/2 = 8
17. The average weight of 9 mangoes increases by 20 g if one of them weighing 120 g is replaced by another. The weight of the new mango is :. [AssistaDt Grade]
180 g 260 g
200 g 300 g
Answer & Explanation
Answer: 300 g
Explanation: Total weight increased (9*20) gm = 180 gm.
Weight of new mango = (120 + 180) gm = 300gm.
18. The average of first five prime numbers is:. [Assistant Grade]
5.4 5.7
5.6 7.5
Answer & Explanation
Answer: 5.6
Explanation: aveage = (2 + 3 +5 + 7 + 11)/5 = 5.6
19. The average of two numbers is M. If one number is N, then the other number is. [Assistant Grade]
2N M—N
2M 2M—N
Answer & Explanation
Answer: 2M—N
Explanation: Sum of two numbers = 2M.
other number = (2M—N)
20. Out of four numbers, the average of first three is 16 and that of the last three is 15. If the last number is 18, the first number is
20 23
21 25
Answer & Explanation
Answer: 21
Explanation: Sum of 2nd and 3rd number = (3*15 - 18) = 27.
First number = (3*16 - 27) = 21.
21. The average weight of 6 men decreases by 3 kg when one of them weighing 80 kg is replaced by a new man. The weight of the new man . [LJ.D.C. Exam 19]
56 kg 62 kg
58 kg 76 kg
Answer & Explanation
Answer: 62 kg
Explanation: Total weight decreased = (6*3) kg = 18 kg. Weight of new man = (80 - 18) kg =
62 kg.
22. The average of all odd numbers upto 100 is:
51 48.5
50 49.2
Answer & Explanation
Answer: 50
Explanation: Sum of odd numbers upto 100
=1+3+5+7+...+95+97+99 =(1+99)+(3+97)+(5+95)+ . ..upto 25 pairs.
=100+100+100+ ...(25times)=2500.
Average = 2500 / 50 = 50.
23. In seven given numbers, the average of first four numbers is 4 and that of the last four numbers is also 4. If the average of these seven numbers is 3, the fourth number is :. [I.Tax and Centr]
3 7
4 11
Answer & Explanation
Answer: 11
Explanation: Fourth number=(4*4 + 4*4 - 7*3) = 11.
24. Three years ago, the average age of a family of 5 members was 17 years. A baby having been born, the average age of the family is the same today . The present age of the baby is: . [Assistant Grade]
2 yrs 3 yrs
2.4 yrs 1.5 yrs
Answer & Explanation
Answer: 2 yrs
Explanation: Total age of 5 members, 3 years ago = (17 x 5) = 85 years.
Total age of 5 members now = (85 + 3 x 5) = 100 years.
Total age of 6 members now = (17 x 6) = 102 years.
Age of the baby =2 years.
5. The average of 50 numbers is 38. If two numbers, namely 45 and 55 are discarded, the average of the remaining numbers is :. [C.B.I. 1990]
36.5 37.5
37 37.52
Answer & Explanation
Answer: 37.5
Explanation: Totalsumof48 numbers =[50*38 - (45+55)] = 1800.
Required average = 1800 / 48 = 37.5.
26. The average of 11 observations is 60. If the average of first five observations is 58 and that of the last five is 56, then the sixth observation is. [Assistant Grade]
90 85
110 100
Answer & Explanation
Answer: 90
Explanation: Sixth observation=[60*11 - (58*5 + 56*5)] = 90.
27. The average of first 50 natural numbers is
11.5 25.5
22.5 25
Answer & Explanation
Answer: 25.5
Explanation: Sum of first n natural numbers n(n + 1)/2
So, average of first n natural numbers n(n + 1)/2n = (n + 1)/2
⇒ (50 + 1)/2 = 25.5
28. The average age of a committee of eight members is 40 years. A member aged 55 years retired and his place was taken by another member aged 39 years. The average age of the present committee is:. [Teacher’s Exam ]
39 years 36 years
38 years 35 years
Answer & Explanation
Answer: 38 years
Explanation: Required average = (8*40 - 55*39)/8 = 38 years.
29. The average weight of 3 men A, B and C is 84 kg. Another man D joins the group and the average now becomes 80 kg. If another man F, whose weight is 3 kg more than that of D, replaces A then the average weight of B, C, D and E becomes 79 kg. The weight of A is:. [Bank P.O. 1989]
70 kg 75 kg
72 kg 80 kg
Answer & Explanation
Answer: 75 kg
Explanation: A+B+C = (84x3) = 252kg, A+B+C+D=(80x4) = 320kg.
D = (320 - 252) = 68 , E = (68+3) =7l.
B+C+D+E = (79x4)=316.
(A+B+C+D) -(B+C+D+E)=(320 - 316)kg = 4kg.
A - E = 4 = A = (4+E)=75kg.
30. In a cricket eleven, the average of eleven players is 28 years. Out of these, the average ages of three groups of three players each are 25 years, 28 years and 30 years respectively. If in these groups, the captain and the youngest player are not included, and the captain is eleven years older than the youngest player, what is the age of the captain ?. [Hotel Managemen]
33 years 35 years
34 years 36 years
Answer & Explanation
Answer: 35 years
Explanation: Let the age of youngest player be x.
Then, age of the captain = (x + 11).
3*25 + 3*28 + 3*30 + x + x + 11 = 11*28.
⇒ 75+84+90+2x+11=308 so 2x=48 so x=24.
Age of the captain=(x+11) = 35 years.
31. The average of ten numbers is 7. If each nuniber is multiplied by 12, then the average of new set of numbers is :. [Assistant Grade]
7 82
19 84
Answer & Explanation
Answer: 84
Explanation: Average of new set = (12 x 7) = 84.
32. The average of four consecutive even numbers is 27. The largest of these numbers is :. [Assistant Grade]
36 30
32 28
Answer & Explanation
Answer: 30
Explanation: Let the numbers are x, x+2, x+4 and x+6. Then,
(x+x+2+x+4+x+6)/4 = 27 ⇒ 4x+ 12/4 = 27 ⇒ x + 3 = 27 ⇒ x = 24
Largest number = (x + 6) = 24 + 6 = 30.
33. Five years ago, the average age of A, B, C and D was 45 years. With E joining them now, the average of all the five is 49 years. How old is E? . [Bank P.O. 1988]
25 years 45 years
40 years 64 years
Answer & Explanation
Answer: 45 years
Explanation: (A+B+C+D), five years ago =(45*4)= l80years.
(A+B+C+D), now = (180 + 5*4) years = 200 years.
A+B+C+D+E, now = (49x5)years=245years.
E, now = (245—200)=45years.
34. If a, b, c, d, e are five consecutive odd numbers, their average Is: . [Bank P.O. 1989]
5(a + 4) 5(a+b+c+d+e)
abcde (a + 4)
Answer & Explanation
Answer: (a + 4)
Explanation: Clearly,b=a+2,c=a+4,d=a+6 and e=a+8.
Average (a + (a + 2) + (a + 4) + (a + 6) + (a + 8)) / 5 = (5a + 20) / 5 = (a + 4)
35. Of the three numbers, second is twice the first and is also thrice the third. If the average of the three numbers is 44, the largest number is:. [I Tax and Centr]
24 72
36 108
Answer & Explanation
Answer: 24
Explanation: Let 3rd number is x. Then, second number = 3x.
First number = 3x / 2
(x + 3x + 3x)/2 = (44*3) or 11x/2 = 44*3 or x=24.
36. The average salary per month of 30 employees in a compnaY is Rs 4000. If the manager’s salary is added, the average salary iicreaSeS to Rs 4300, what is the salary of the manager. [Bank P.O. 1993]
Rs 10000 Rs 12000
Rs 13000 Rs 13300
Answer & Explanation
Answer: Rs 13300
Explanation: Salary of the manager = (31*4300 - 30*4000) =
13300.
1. The average of 50 numbers is 38. If two numbers, namely 45 and 55 are discarded, the average of the remaining
numbers is :. [C.B.I. 1990]
36.5 37.5
37 37.52
Answer & Explanation
Answer: 37.5
Explanation: Totalsumof48 numbers =[50*38 - (45+55)] = 1800.
Required average = 1800 / 48 = 37.5.
2. The mean of 1², 2², 3², 4², 5², 6², 7² is:. [U.D.C. Exam 199]
40 30
20 10
Answer & Explanation
Answer: 20
Explanation: sum of square of first n numbers n(n + 1)(2n + 1)/6
⇒ 7(7 + 1)(7*2 + 1)/6 = 140
average = 140/7 = 20
3. The average of first 50 natural numbers is
11.5 25.5
22.5 25
Answer & Explanation
Answer: 25.5
Explanation: Sum of first n natural numbers n(n + 1)/2
So, average of first n natural numbers n(n + 1)/2n = (n + 1)/2
⇒ (50 + 1)/2 = 25.5
4. A motorist travels to a place 150 km away at an average speed of 50 km per hour and returns at 30 km per hour.
His average speed for the whole journey in km per hour is :. [Bank P.O. 1991]
35 37.5
37 40
Answer & Explanation
Answer: 37.5
Explanation: Average speed = 2xy/(x + y) km/hr = 2*50*30/(50 + 30) = 37.5 km/hr
5. The average age of 30 students is 9 years. If the age of their teacher is included, it becomeS 10 years. The age of
the teacher (in years)is :. [Assistant Grade]
27 35
31 40
Answer & Explanation
Answer: 40
Explanation: Age of the teacher = (31*10 + 30*9) = 40 years.
6. In seven given numbers, the average of first four numbers is 4 and that of the last four numbers is also 4. If the
average of these seven numbers is 3, the fourth number is :. [I.Tax and Centr]
3 7
4 11
Answer & Explanation
Answer: 11
Explanation: Fourth number=(4*4 + 4*4 - 7*3) = 11.
7. The average of two numbers is M. If one number is N, then the other number is. [Assistant Grade]
2N M—N
2M 2M—N
Answer & Explanation
Answer: 2M—N
Explanation: Sum of two numbers = 2M.
other number = (2M—N)
8. The average of eight numbers is 14. The average of six of these numbers is 16. The average of the remaining two
numbers is: . [Bank P.O. 1994]
4 16
8 Data inadequate
Answer & Explanation
Answer: 8
Explanation: Total sum of remaining two (8*14 - 6*16) = 16.
Average oLthese two numbers = 16/2 = 8
9. Five years ago, the average age of P and Q was 15 years. Average age of F, Q andR today is 20 years. How old
will R be after 10 years?. [Bank P.O. 1989]
35 yrs 30 yrs
40 yrs 50 yrs
Answer & Explanation
Answer: 30 yrs
Explanation: (P + Q), five years ago = (15 * 2) = 30 years.
(P+Q), now = (30+5*2)years=40years.
(P + Q + R), now = (20 x 3) years =60 years.
R, now = (60 - 40) years = 20 years.
R, after 10 years = (20 + 10) years =30 years.
10. The average of ten numbers is 7. If each nuniber is multiplied by 12, then the average of new set of numbers is
:. [Assistant Grade]
7 82
19 84
Answer & Explanation
Answer: 84
Explanation: Average of new set = (12 x 7) = 84.
11. Three years ago, the average age of a family of 5 members was 17 years. A baby having been born, the average
age of the family is the same today . The present age of the baby is: . [Assistant Grade]
2 yrs 3 yrs
2.4 yrs 1.5 yrs
Answer & Explanation
Answer: 2 yrs
Explanation: Total age of 5 members, 3 years ago = (17 x 5) = 85 years.
Total age of 5 members now = (85 + 3 x 5) = 100 years.
Total age of 6 members now = (17 x 6) = 102 years.
Age of the baby =2 years.
12. Out of four numbers, the average of first three is 16 and that of the last three is 15. If the last number is 18, the
first number is
20 23
21 25
Answer & Explanation
Answer: 21
Explanation: Sum of 2nd and 3rd number = (3*15 - 18) = 27.
First number = (3*16 - 27) = 21.
13. In a cricket eleven, the average of eleven players is 28 years. Out of these, the average ages of three groups of
three players each are 25 years, 28 years and 30 years respectively. If in these groups, the captain and the
youngest player are not included, and the captain is eleven years older than the youngest player, what is the age of
the captain ?. [Hotel Managemen]
33 years 35 years
34 years 36 years
Answer & Explanation
Answer: 35 years
Explanation: Let the age of youngest player be x.
Then, age of the captain = (x + 11).
3*25 + 3*28 + 3*30 + x + x + 11 = 11*28.
⇒ 75+84+90+2x+11=308 so 2x=48 so x=24.
Age of the captain=(x+11) = 35 years.
14. The average age of a committee of eight members is 40 years. A member aged 55 years retired and his place
was taken by another member aged 39 years. The average age of the present committee is:. [Teacher’s Exam ]
39 years 36 years
38 years 35 years
Answer & Explanation
Answer: 38 years
Explanation: Required average = (8*40 - 55*39)/8 = 38 years.
15. A team of 8 persons joins in a shooting competition. The best marksman scored 85 points. If he had scored 92
points; the average score for the team would have been 84. The number of points, the team scored, was :.[C.B.I.
1993]
672 645
665 588
Answer & Explanation
Answer: 665
Explanation: Let the total score be x.
(x +92 - 85)/8 = 84 so x+7 = 672 so x=665
16. A man whose bowling average is 12.4, takes 5 wickets for 26 runs and ther eby decreases his average by 0.4.
The number of wickets, taken by him before his last match is :. [C.B.I. 1991]
85 72
78 64
Answer & Explanation
Answer: 85
Explanation: Let the number of wickets taken before the last match is x.
Then, (l2.4x + 26)/(x + 5) = 12 ⇒ l2.4x+26=12x+60
⇒ 0.4x=34 ⇒ x = 34/0.4 = 85
17. The average of all odd numbers upto 100 is:
51 48.5
50 49.2
Answer & Explanation
Answer: 50
Explanation: Sum of odd numbers upto 100
=1+3+5+7+...+95+97+99 =(1+99)+(3+97)+(5+95)+ . ..upto 25 pairs. =100+100+100+
...(25times)=2500.
Average = 2500 / 50 = 50.
18. The mean of 100 observations was calculated as 40. It was found later on that one of the observations was
misread as 83 instead of 53. The correct mean is :. [C.B.I. 1993]
39 40.3
39.7 42.7
Answer & Explanation
Answer: 39.7
Explanation: Correct sum = (40*100 + 53 - 83) = 3970.
Correct mean = 3970/100 = 39.7
19. The average of four consecutive even numbers is 27. The largest of these numbers is :. [Assistant Grade]
36 30
32 28
Answer & Explanation
Answer: 30
Explanation: Let the numbers are x, x+2, x+4 and x+6. Then,
(x+x+2+x+4+x+6)/4 = 27 ⇒ 4x+ 12/4 = 27 ⇒ x + 3 = 27 ⇒ x = 24
Largest number = (x + 6) = 24 + 6 = 30.
20. The average of Kanchans marks in 7 subjects is 75. His average in six subjects excluding Science is 72. How
many marks did he get in Science? . [Bank P.O., 1993]
72 93
90 100
Answer & Explanation
Answer: 93
Explanation: Marks in Science (7*75 - 6-72) = 93.
26. The average salary per month of 30 employees in a compnaY is Rs 4000. If the manager’s salary is added, the
average salary iicreaSeS to Rs 4300, what is the salary of the manager. [Bank P.O. 1993]
Rs 10000 Rs 12000
Rs 13000 Rs 13300
Answer & Explanation
Answer: Rs 13300
Explanation: Salary of the manager = (31*4300 - 30*4000) = 13300.
27. There are three sections of a class in a school. The number of students in the three sections is 38, 32 and 40
and the average age of the students in these sections separately is 15.3 years, 16.5 years and 15.9 years
respectively. What is the average age of the class?. [Hotel Managemen]
15.9 yrs 15.96 yrs
15.92 yrs 15.86 yrs
Answer & Explanation
Answer: 15.86 yrs
Explanation: average = (38*15.3 + 32*16.5 + 40*15.9)/(38+32+40) = 1745.4/110 = 15.867
28. The average of 11 observations is 60. If the average of first five observations is 58 and that of the last five is 56,
then the sixth observation is. [Assistant Grade]
90 85
110 100
Answer & Explanation
Answer: 90
Explanation: Sixth observation=[60*11 - (58*5 + 56*5)] = 90.
29. The average age of 40 student of a class is 15 year. When 10 new students are admitted, the average is
increased by 0.2 years. The average age of new students is :. [AssistaDt Grade]
15.2 yrs 16.2 yrs
16 yrs 16.4 yrs
Answer & Explanation
Answer: 16 yrs
Explanation: Sum of ages of 10 new students = (50*15.2 - 40*15) = 160 years
. Average age of new students = 160/10 = 16 years.
30. Of the three numbers, second is twice the first and is also thrice the third. If the average of the three numbers is
44, the largest number is:. [I Tax and Centr]
24 72
36 108
Answer & Explanation
Answer: 24
Explanation: Let 3rd number is x. Then, second number = 3x.
First number = 3x / 2
(x + 3x + 3x)/2 = (44*3) or 11x/2 = 44*3 or x=24.
31. The average of first five prime numbers is:. [Assistant Grade]
5.4 5.7
5.6 7.5
Answer & Explanation
Answer: 5.6
Explanation: aveage = (2 + 3 +5 + 7 + 11)/5 = 5.6
32. The average age of 30 students of a class is 12 years. The average age of a group of 5 of the students is 10
years and that of another gfoup of 5 of them is 14 years. What is the average age oi the remaining
students?.[Bank P.O. 1990]
8 years 12 years
10 years 14 years
Answer & Explanation
Answer: 12 years
Explanation: Total age of 20 students = (30 * 12) - (5*10 + 5*14)= 240 years.
Required average = (240/20) = 12 years.
33. The average of first five multiples of 3 is:. [I.Tax and Cent]
3 8
6 9
Answer & Explanation
Answer: 9
Explanation: average = (1 + 2 + 3 + 4 + 5) * 3/5 = 15 * 3 / 5 = 9
34. The average weight of 3 men A, B and C is 84 kg. Another man D joins the group and the average now
becomes 80 kg. If another man F, whose weight is 3 kg more than that of D, replaces A then the average weight
of B, C, D and E becomes 79 kg. The weight of A is:. [Bank P.O. 1989]
70 kg 75 kg
72 kg 80 kg
Answer & Explanation
Answer: 75 kg
Explanation: A+B+C = (84x3) = 252kg, A+B+C+D=(80x4) = 320kg.
D = (320 - 252) = 68 , E = (68+3) =7l.
B+C+D+E = (79x4)=316.
(A+B+C+D) -(B+C+D+E)=(320 - 316)kg = 4kg.
A - E = 4 = A = (4+E)=75kg.
35. The average age of boys in the class is twice the number of girls in the class. If the ratio of boys and girls in
the class of 36 be 5 : 1, what is the total of the ages (in years) of the boys in the class. [Bank P.O. 1989]
490 420
196 360
Answer & Explanation
Answer: 360
Explanation: Number of boys = 136 *(5/2) = 30,
Number of girls 6.
Average age of boys = (2 * 6) = 12 years.
Total age of boys (30 * 12) years = 360 years.
6. The average weight of 6 men decreases by 3 kg when one of them weighing 80 kg is replaced by a new man. The
weight of the new man . [LJ.D.C. Exam 19]
56 kg 62 kg
58 kg 76 kg
Answer & Explanation
Answer: 62 kg
Explanation: Total weight decreased = (6*3) kg =
18 kg. Weight of new man = (80 -
18) kg = 62 kg.
1. In the first 10 overs of a cricket game, the run rate was only 3.2. What should be the run
rate in the remaining 40 overs to reach the target of 282 runs?
A. 6.25 B. 6.5
C. 6.75 D. 7
Answer & Explanation
Answer: Option A
Explanation:
Required run rate =
282 - (3.2 x 10)
=
250
= 6.25
40 40
2. A family consists of two grandparents, two parents and three grandchildren. The average age of
the grandparents is 67 years, that of the parents is 35 years and that of the grandchildren is 6
years. What is the average age of the family?
A.
28
4
years
7
B.
31
5
years
7
C.
32
1
years
7
D. None of these
Answer & Explanation
Answer: Option B
Explanation:
Required average
=
67 x 2 + 35 x 2 + 6 x 3
2 + 2 + 3
=
134 + 70 + 18
7
=
222
7
= 31
5
years.
7
3. A grocer has a sale of Rs. 6435, Rs. 6927, Rs. 6855, Rs. 7230 and Rs. 6562 for 5 consecutive
months. How much sale must he have in the sixth month so that he gets an average sale of Rs.
6500?
A. Rs. 4991 B. Rs. 5991
C. Rs. 6001 D. Rs. 6991
Answer & Explanation
Answer: Option A
Explanation:
Total sale for 5 months = Rs. (6435 + 6927 + 6855 + 7230 + 6562) = Rs. 34009.
Required sale = Rs. [ (6500 x 6) - 34009 ]
= Rs. (39000 - 34009)
= Rs. 4991.
4. The average of 20 numbers is zero. Of them, at the most, how many may be greater than zero?
A. 0 B. 1
C. 10 D. 19
Answer & Explanation
Answer: Option D
Explanation:
Average of 20 numbers = 0.
Sum of 20 numbers (0 x 20) = 0.
It is quite possible that 19 of these numbers may be positive and if their sum is athen 20th
number is (-a).
5. The average weight of 8 person's increases by 2.5 kg when a new person comes in place of one of
them weighing 65 kg. What might be the weight of the new person?
A. 76 kg B. 76.5 kg
C. 85 kg D. Data inadequate
E. None of these
Answer & Explanation
Answer: Option C
Explanation:
Total weight increased = (8 x 2.5) kg = 20 kg.
Weight of new person = (65 + 20) kg = 85 kg.
. The captain of a cricket team of 11 members is 26 years old and the wicket keeper is 3 years
older. If the ages of these two are excluded, the average age of the remaining players is one year
less than the average age of the whole team. What is the average age of the team?
A. 23 years B. 24 years
C. 25 years D. None of these
Answer & Explanation
Answer: Option A
Explanation:
Let the average age of the whole team by x years.
11x - (26 + 29) = 9(x -1)
11x - 9x = 46
2x = 46
x = 23.
So, average age of the team is 23 years.
7. The average monthly income of P and Q is Rs. 5050. The average monthly income of Q and R is
Rs. 6250 and the average monthly income of P and R is Rs. 5200. The monthly income of P is:
A. 3500 B. 4000
C. 4050 D. 5000
Answer & Explanation
Answer: Option B
Explanation:
Let P, Q and R represent their respective monthly incomes. Then, we have:
P + Q = (5050 x 2) = 10100 .... (i)
Q + R = (6250 x 2) = 12500 .... (ii)
P + R = (5200 x 2) = 10400 .... (iii)
Adding (i), (ii) and (iii), we get: 2(P + Q + R) = 33000 or P + Q + R = 16500 .... (iv)
Subtracting (ii) from (iv), we get P = 4000.
P's monthly income = Rs. 4000.
8. The average age of husband, wife and their child 3 years ago was 27 years and that of wife and
the child 5 years ago was 20 years. The present age of the husband is:
A. 35 years B. 40 years
C. 50 years D. None of these
Answer & Explanation
Answer: Option B
Explanation:
Sum of the present ages of husband, wife and child = (27 x 3 + 3 x 3) years = 90 years.
Sum of the present ages of wife and child = (20 x 2 + 5 x 2) years = 50 years.
Husband's present age = (90 - 50) years = 40 years.
9. A car owner buys petrol at Rs.7.50, Rs. 8 and Rs. 8.50 per litre for three successive years. What
approximately is the average cost per litre of petrol if he spends Rs. 4000 each year?
A. Rs. 7.98 B. Rs. 8
C. Rs. 8.50 D. Rs. 9
Answer & Explanation
Answer: Option A
Explanation:
Total quantity of petrol
consumed in 3 years
=
4000
+
4000
+
4000
litres
7.50 8 8.50
= 4000
2
+
1
+
2
litres
15 8 17
=
76700
litres
51
Total amount spent = Rs. (3 x 4000) = Rs. 12000.
Average cost = Rs.
12000 x 51
= Rs.
6120
= Rs. 7.98
76700 767
11. The average weight of A, B and C is 45 kg. If the average weight of A and B be 40 kg and that of
B and C be 43 kg, then the weight of B is:
A. 17 kg B. 20 kg
C. 26 kg D. 31 kg
Answer & Explanation
Answer: Option D
Explanation:
Let A, B, C represent their respective weights. Then, we have:
A + B + C = (45 x 3) = 135 .... (i)
A + B = (40 x 2) = 80 .... (ii)
B + C = (43 x 2) = 86 ....(iii)
Adding (ii) and (iii), we get: A + 2B + C = 166 .... (iv)
Subtracting (i) from (iv), we get : B = 31.
B's weight = 31 kg.
12. The average weight of 16 boys in a class is 50.25 kg and that of the remaining 8 boys is 45.15 kg.
Find the average weights of all the boys in the class.
A. 47.55 kg B. 48 kg
C. 48.55 kg D. 49.25 kg
Answer & Explanation
Answer: Option C
Explanation:
Required average
=
50.25 x 16 + 45.15 x 8
16 + 8
=
804 + 361.20
24
=
1165.20
24
= 48.55
13. A library has an average of 510 visitors on Sundays and 240 on other days. The average number
of visitors per day in a month of 30 days beginning with a Sunday is:
A. 250 B. 276
C. 280 D. 285
Answer & Explanation
Answer: Option D
Explanation:
Since the month begins with a Sunday, to there will be five Sundays in the month.
Required average
=
510 x 5 + 240 x 25
30
=
8550
30
= 285
14. If the average marks of three batches of 55, 60 and 45 students respectively is 50, 55, 60, then
the average marks of all the students is:
A. 53.33 B. 54.68
C. 55 D. None of these
Answer & Explanation
Answer: Option B
Explanation:
Required average
=
55 x 50 + 60 x 55 + 45 x 60
55 + 60 + 45
=
2750 + 3300 + 2700
160
=
8750
160
= 54.68
15. A pupil's marks were wrongly entered as 83 instead of 63. Due to that the average marks for the
class got increased by half (1/2). The number of pupils in the class is:
A. 10 B. 20
C. 40 D. 73
Answer & Explanation
Answer: Option C
Explanation:
Let there be x pupils in the class.
Total increase in marks = x x
1
=
x
2 2
x
= (83 - 63)
x
= 20 x= 40.
2 2
1. Average:
Average = Sum of observations
Number of observations
2. Average Speed:
Suppose a man covers a certain distance at x kmph and an equal distance at ykmph.
Then, the average speed druing the whole journey is 2xy
kmph.x + y