Algebra 1 Notes

3.7 Percent of Change

Example 1

25x25700

25

100

x

25

7100

x

25

1825

%100

change of %

amount original

change of amount

original: 25 new: 18 Percent of increase or decrease?Find the percent of change.

Since the new number is less than the original, this is % of decrease.

x%28

Example 2• original: 50 new: 70 Percent of increase or decrease?• Find the percent of change.

%100

change of %

amount original

change of amount

70 50

50 10020

50 100

x

x

2000 50x

40% = r

Example 3

%100

change of %

amount original

change of amount

c25600c100100

25

c

6c

c75600

75

grams 8c

To be marked “reduced fat” a food must have at least 25% less fat than the same full fat food. If one ounce of reduced fat chips has 6 grams of fat less than the full fat chips, what is the least amount of fat in one ounce of regular chips?

c100 c100

75

Discounts and mark ups

• To figure a discount: – SUBTRACT the percentage of the discount

from 100%– convert to a decimal– then multiply this by the price of the item.

• To figure a mark up: – ADD the percentage of the mark up to 100%– convert to a decimal– then multiply this by the price of the item.

Example 4

)95.175%(5579.18

or )95.175%(45

Find the discounted price. Suit: $175.95; Discount: 45%

18.7995.175

77.96$

Example 5

)95.39%(75.6)95.39%(75.106 or70.2

Find the total price. Clock: $39.95; Tax: 6.75%

95.3970.2

65.42$