Question

Identify the percent of change as an increase or decrease. Then find the percent of change. Round to the nearest tenth of a percent, if necessary.
4. 12 inches to 36 inches 7. 24 songs to 78 songs 10. 16cm to 44.2cm
5. 75 people to 25 8. 10 gallons to 24 gallons 11. 68 miles to 42.5 miles
6. 50 pounds to 35 pounds 9. 72 paper clips to 63 paper clips

Answer 1

I'll do the first two problems to get you started. All problems shown will use the same formula.

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Problem 4

The formula to use is

C = 100*(B-A)/A

where

A = old value

B = new value

C = percent change

In this case, A = 12 and B = 36, so

C = 100*(B-A)/A

C = 100*(36-12)/12

C = 100*(24/12)

C = 100*2

C = 200%

We have a 200% increase. It is an increase because the value of C is positive.

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Problem 5

Use the same formula as in the previous problem. This time,

A = 75 is the old value

B = 25 is the new value

C = 100*(B-A)/A

C = 100*(25-75)/75

C = 100*(-50/75)

C = 100*(-2/3)

C = -66.6667%

C = -66.7%

The value of C is negative, so we have a percent decrease of roughly 66.7%