Respect Responsibility Readiness
1. The price of an Instazoom camera increased from $75 to $90. Find the percent of increase in
price.
Solution
To find the percent of increase or decrease.
First find the change and then divide the change by the original amount.
The change here is 15
The original amount is 75
15/75 is .2
.2 = 20%
The percent of increase is 20%
2. The number of students
attending Sky High School increased from 1600 to 1800. What was the percent of
increase?
Solution
To find the percent of increase or decrease.
First find the change and then divide the change by the original amount.
The change here is 200
The original amount is 1600
200/1600 is .125
.125 = 12.5%
The percent of increase is 12.5%
3. Because of improved
technology, the time needed to manufacture an XYZ machine has fallen from 20
hours to 9 hours. Find the percent of decrease.
Solution
To find the percent of increase or decrease.
First find the change and then divide the change by the original amount.
The change here is 11
The original amount is 20
11/20 is .55
.55 = 55%
The percent of decrease is 55%
4. After two weeks on the
Try-No-Meal Diet, Terry’s weight dropped from 60 kg to 54 kg. Find the percent
of decrease.
Solution
To find the percent of increase or decrease.
First find the change and then divide the change by the original amount.
The change here is 6
The original amount is 60
6/60 is .1
.1 = 10%
The percent of decrease is 10%
5. During one year, the
value of a diamond increased 25%. If the diamond was originally worth $3000,
what was it worth one year later?
Solution
In this problem multiply the original amount (3000) by 1.25
3000 times 1.25 = 3750
So 1 year later the diamond is worth $3750
6. During June a car dealer
sold 250 new cars. During July he sold 14% fewer cars. How many cars did he sell
in July?
Solution
In this problem if he sold 14% fewer cars then he did sell 86%
So 250 times .86 = 215
So the car dealer sold 215 cars.
7. At the close of one
business day, TNT stock was trading at $40 per share. At the close of the next
business day, the stock was trading at $46 per share. Find the percent of
increase.
Solution
To find the percent of increase or decrease.
First find the change and then divide the change by the original amount.
The change here is 6
The original amount is 40
6/40 is .15
.15 = 15%
The percent of increase is 15%
8. A $150
bicycle is on sale at a 20% discount. If there is a 5% sales tax, how much does the bicycle
cost in all?
Solution
In this problem if the bicycle is at a 20% discount then 80% of the price was kept.
150 times .80 = 120
120 times 1.05 = 126
So the price of the bicycle after the discount and after tax is $126