Answers:

1. Which of the following calculations will tell you the percent increase of a value that changed from 120 to 135?

a. (135-120)/120 Yes. This tells the increase as a percent of 120 (the before number)

b. (135-120)/135 No (this tells the increase as a percent of 135--not what the problem is asking for)

c. 1-(120/135) No (this also tells the increase as a percent of 135--not what the problem is asking for)

d. (135/120)-1 Yes. 135/120 tells 135 as a percent of 120 (the before number). When you subtract 1, that tells the amount it increased.

2. Pat exercised for a month, and her weight changed from 150 lbs to 140 lbs. By what percent did her weight decrease?

150-140=10

10/150 = .06667.

Her weight decreased by 6.7%.

3. Mike's bank ballance changed from $2500 at the beginning of one month to $1900 at the beginning of the next month. Find the percent that fills the blank in the following statement:

1900/2500 (always divide by the number that represents what it is a percent of)

1900/2500=.076

Mike's bank ballance is ___7.6____% of the ballance last month.

4. A. Kara's emporium applied a 25% markup on the wholesale price of decorative candles. If the wholesale price of a candle is $1.30, what price are they being sold for at Kara's?

1.30*.25=.325

Retail price at Kara's: $1.30+.33 = $1.66

B. Kara's is having a sale on the candles described in part A, where they are being sold at wholesale prices. What percent decrease is this from the usual selling price?

The amount decrease is $1.66 - $1.30 = $.33

The percent decrease is .33/1.66=.1988 This is approximately 20% less than the usual selling price

5. The price of Fred's favorite cereal increased from $1.75 to $2.10. By what percent did it increase?

Amount of increase is 2.10 - 1.75 = .35

.35/1.75 (divide by the "before" value)

.35/1.75=.2

It increased by 20%

6. The amount of phosphorous dissolved in the water of a certain lake increased from .015 mg/L to .048 mg/L. By what percent did the phosphorous increase?

Amount of increase: .048 - .015 = .033

Percent of increase = .033/.015 = 2.2. It increased by 220%

7. A. In the month of February, the gross income (receipts) of Kara's emporium was $21,500. In March, the gross income was $20,000. By what percent did the gross income decrease fom February to March?

Amount of decrease

B. In April, the gross income was back up to what it was in February ($21,500). By what percent did the gross income increase from March to April?