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First things First:
Average
Average =
, , , , , ( +++ = ) , = / =
, , , , , =
01.UCBL-210 The average age of group of 10 students is 15 years.
When 5 new students joined the group, the average age rose by 1
year, The average age (in years) of the new student is:
a) 18 years b) 17 years c) 16 years d) None of these Detail
Solution Short-Cut = , = = + = + = , = = = = , = / =
= +
=
Average
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02. BB-2009 Three math classes, X, Y, and Z, take an algebra
test. The average score in class X is 83. The average score in
class Y is 76. The average score in class Z is 85. The average
score of all students in classes X and Y together is 79. The
average score of all students in classes Y and Z together is 81.
What is the average for all the three classes? a) 81 b) 81.5 c) 82
d) 84.5 e) None of these Detail Solution X = x Y = y Z = z , X Y ,
x* + y* = *(x+y)
* x + *y = *x+*y , * x- *x= *y-*y , *x = *y , x:y=: ---- () , Y
Z , y* + z* = *(y+z)
*y + z* = *y+* z , *y - *y = z*-* z , *y = *z , y:z = :
--------() , () () , x:y:z= 3:5:4 , = ++
++ = .
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03. Dhaka Bank-2010 At New Market fruit stand, the price of each
apple is taka 40 and the price of each orange is taka 60. Munir
selects a total of 10 apples and oranges from the fruit stand, and
the average price of the 10 pieces of fruit is taka 56. How many
oranges must Munir put back and replace with apples so that the
average price of the pieces of fruit that he keeps is taka 52?
A) 1 B) 2 C) 3 D) 4 E) None of these Detail Solution , , * + * =
(+)* , * + * = * + * , * * = *- * , * = * , = : = : ,
, , , * + * = (+)* , * + * = * + * , * * = *- * , * = * , = : =
: ,
- =
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04. Social Islami Bank2011 Having scored 98 runs in the 19th
innings, a cricketer increases his average score by 4. What will be
his average score after the 19th innings? A. 22 B. 24 C. 28 D. 26
E. None of the above Detail-Solution , , ( ) , = = * = (+) , + = ,
* + = (+)* , * + = * + * , = , = + = 05. Mercantile Bank-2011 The
arithmetic mean of the 5 consecutive integers starting with p is q.
What is the arithmetic mean of 9 consecutive integers that start
with (p + 2)?
a. 2 + p + q b. 2 + q c. 2q + 2 d.. 4 + q e. None of these
Detail Solution , p , p+(p+)+(p++)+(p+++)+(p++++)= * q , p =
(5*q-10)/5 = q-2
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, (P+2) {(P+2)+ (P+3)+ (P+4)+ (P+5)+ (P+6)+ (P+7)+ (P+8)+ (P+9)+
(P+10)}/9 , (9P+54)/9 = P+6 , p- q-2 , = q-2+6 = q+4 Short-Cut:
