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05 – 04C PERCENTS
PERCENT OF DECREASE OR
INCREASE
New – OldOld
Negative answer => Decrease
Positive answer => Increase
OldNew
August hosted two dinner parties for his friends. Twenty guests attended the first party, and twenty-nine guests attended the second party. What is the percentage increase of the number of guests from the first party to the second party?
PERCENT OF DECREASE OR
INCREASE
New – OldOld
Negative answer => Decrease
Positive answer => Increase
An item is priced at $13.24. If the sales tax is 4%, what does the item cost including sales tax?
SALES TAX
Multiply price by sales tax (decimal) $13.24 × 0.04 = $0.53(round to nearest penny)
Now, add the tax to the full price. $13.24 + $0.53 = $13.77
Dave rented a limousine for his wife's birthday. The hourly rate is $80. They used the limousine for 4 hours, plus Dave gave the driver a 20% tip. How much did he spend in total
for the hourly charges plus tip?
BILL PLUS TIP
First, find the total for the hourly charges.hourly rate × hours used = $80 × 4 = $320
Next, determine the tip on that total.20% of $320 = 0.2 × $320 = $64
Finally, find the total of the hourly charges plus the tip.
$320 + $64 = $384
Tonya took out a loan to help pay for her house. She borrowed $30,000 for 15 years at a yearly simple interest rate of 5%. How much interest will she end up paying the
bank?
INTEREST
The formula for computing simple interest is shown below, where p is the principal (starting) amount, r is the interest rate (in decimal form), and t is the time (in years).
I = prtThe principal is $30,000, the time is 15 years, and the interest rate is 5%, or 0.05.
I =
($30,000)(0.05)(15 yr)
=
$22,500
Tonya took out a loan to help pay for her house. She borrowed $30,000 for 15 years at a yearly simple interest rate of 5%. How much interest will she end up paying the
bank?
INTEREST
The formula for computing simple interest is shown below, where p is the principal (starting) amount, r is the interest rate (in decimal form), and t is the time (in years).
I = prtThe principal is $30,000, the time is 15 years, and the interest rate is 5%, or 0.05.
I =
($30,000)(0.05)(15 yr)
=
$22,500
Tonya took out a loan to help pay for her house. She borrowed $30,000 for 15 years at a yearly simple interest rate of 5%. How much interest will she end up paying the
bank?
INTEREST
The formula for computing simple interest is shown below, where p is the principal (starting) amount, r is the interest rate (in decimal form), and t is the time (in years).
I = prtThe principal is $7,000, the rate is 3%, or 0.03, and the interest is $1,050.
Tonya took out a loan to help pay for her house. She borrowed $30,000 for 15 years at a yearly simple interest rate of 5%. How much interest will she end up paying the
bank?
INTEREST
The formula for computing simple interest is shown below, where p is the principal (starting) amount, r is the interest rate (in decimal form), and t is the time (in years).
I = prtThe principal is $7,000, the rate is 3%, or 0.03, and the interest is $1,050.
Bert is planning to open a savings account that earns 1.6% simple interest yearly. He
wants to earn exactly $288 in interest after 3 years. How much money should he deposit?
INTEREST
The formula for computing simple interest is shown below, where p is the principal (starting) amount, r is the interest rate (in decimal form), and t is the time (in years).
I = prtThe desired interest is $288, the time is 3 years, and the interest rate is 1.6%, or 0.016.
Holly missed 6 of 180 school days this year. Approximately what percent of school days was Holly in attendance?
FIND A PERCENT
First, determine how many school days Holly attended.180 - 6 = 174
Next, find the percentage of school days she attended.174 ÷ 180 = 0.9666666667
= 97%
Kathleen had a bag of candy-coated chocolates. Of the 60 candies in the bag, 20% were red, 30% were orange, 30% were green, and 20% were
blue. Of the blue ones, 10% had a damaged candy coating. Approximately how many of the blue ones had a damaged candy coating?
DAMAGED ITEMS
First, determine how many of the candies were blue.20% of 60 = 0.2 × 60 = 12
Next, find how many of the blue ones were damaged.10% of 12 = 0.1 × 12 = 1.2
Approximately 1 of the blue ones had a damaged candy coating.
Nathan took his car in for service and repairs. He had a coupon for 10% off.
Original Prices
Labor $288.37
Parts $397.03
Other $67.18
Which amount is closest to Nathan's total costs after the 10% discount and including 7% sales tax? [Assume tax is applied after
the discount is applied.]
COUPONS
First, find the total cost for service and repairs.$288.37 + $397.03 + $67.18 = $752.58
$752.58 - 0.1($752.58) = $752.58 - $75.26
= $677.32
Next, determine the total after the 10% discount.
Finally, apply the 7% sales tax.
$677.32 + 0.07($677.32)
= $677.32 + $47.41
= $724.73
COUPONS CONT.
The value of a professional basketball player's autograph rose 30% in the last year. It is now worth $364.00. What
was it worth a year ago?
PERCENTS
(1 + 30%). Convert 30% to 0.3.
$364.00 ÷ (1 + 0.3) = $280.00
Jessica purchased a sapphire bracelet during the Jewelry Emporium's Semi-Annual Clearance Sale. If Jessica paid
$182.00 for the bracelet and the original price is $260.00, how much of a discount did she receive?
% OF DISCOUNT
Original Price - Discount = Sale Price$260.00 - ($260.00 × p) = $182.00
-$260.00p = -$78.00$260.00p = $78.00
p = $78.00 ÷ $260.00p = 0.3p = 30%
Molly is having her birthday party at Pizza Party Palace. The costs involved are listed below. Pizza Party Palace
requires a 20% deposit prior to the date of the event. If the deposit has been paid, how much is still owed for Molly's
party?
DEPOSIT, HOW MUCH IS STILL OWED
• Food & Drink$20
0
• Game Tokens$10
0• Other $60
First, find the total of all party costs.$200 + $100 + $60 = $360Next, find 20% of $360.20% of $360 = 0.2 × $360 = $72
$360 - $72 = $288
• 6-ounce $9.95• 8-ounce $12.95
•11-ounce
$15.95
MEALS AND GRATITUITY
Brad had a small gathering at a local steakhouse. The steakhouse offers three dinner platters which vary by size and price. They ordered 4 of the 6-ounce platters, 2 of the 8-ounce platters, and 2 of the 11-ounce platters.Steak Platter Prices
If a gratuity of 18% was added to the bill, which of the following is closest to the total of the steak platters and gratuity, ignoring sales tax?
4($9.95) + 2($12.95) + 2($15.95)
$39.80 + $25.90 + $31.90 =
=
$97.60
First, find the total cost for all dinner platters.
MEALS AND GRATITUITY
Brad had a small gathering at a local steakhouse. The steakhouse offers three dinner platters which vary by size and price. They ordered 4 of the 6-ounce platters, 2 of the 8-ounce platters, and 2 of the 11-ounce platters.Steak Platter Prices
If a gratuity of 18% was added to the bill, which of the following is closest to the total of the steak platters and gratuity, ignoring sales tax?
Next, determine the 18% gratuity.18% of $97.60 = 0.18 × $97.60
$17.57
$17.57
Finally, find the sum of the dinner platters plus the gratuity.
$97.60 + $17.57 = $115.17
In his free time, Gary spends 12 hours per week on the Internet and 7 hours per week playing video games. If Gary
has five hours of free time per day, approximately what percent of his free time is spent on the Internet and playing
video games?
% OF TIME
First, find the total time Gary spends on the Internet and playing video games per week.12 + 7 = 19
Next, determine how much total free time he has each week.5 × 7 = 35
Finally, determine what percent of his free time is spent on the Internet or playing video games.19 ÷ 35 = 0.5428571429
Gary spends approximately 54% of his free time on the Internet and playing video games.
Brian has reduced his cholesterol level by 14% by following a strict diet and regular exercise. If his original level was
300, what is his cholesterol level now?
PERCENTS
Sandy works at a clothing store. She makes $9 per hour plus earns 15% commission on her sales. She worked 70
hours over the last two weeks and had a total of $1,822 in sales before taxes.
Which of the following is closest to how much she will earn in hourly wages and commission for those two weeks?
COMMISSION
First, determine Sandy's earnings based on her hourly wage.hours worked × hourly wage = 70 × $9 = $630Next, determine her commission on her total sales.15% of her total sales = 0.15 × $1,822 = $273.30Finally, find the sum of her hourly wages plus commission.$630 + $273.30 = $903.30
THE END