**Percent Increase/Decrease **

- 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%

- 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%

- 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%

- 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%

- 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

- 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.

- 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%

- 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