## Basic College Mathematics (9th Edition)

Published by Pearson

# Chapter 5 - Ratio and Proportion - 5.2 Rates - 5.2 Exercises - Page 345: 31

#### Answer

The actual cost for a 30 minute call is: Penny Saver \$0.54 Most Minutes \$0.565 USA Card \$0.55 The per minute cost is: Penny Saver \$0.018/min Most Minutes \$0.019/min USA Card \$0.018/min Comparing all 3 providers, the cost per minute is almost identical for a 30 minute call.

#### Work Step by Step

(a) To find the actual total cost, add the connection fee to the per minute charge for 30 minutes. Penny Saver $0.39 + (30)(0.005)$ = $0.39+0.15$ = 0.54 Most Minutes $0.49 + (30)(0.0025)$ = $0.49+0.075$ = 0.565 USA Card $0.25 + (30)(0.01)$ = $0.25+0.30$ = 0.55 (b) Use the actual cost from (a) to find the unit cost. Penny Saver $\frac{0.54}{30 min}$ = $\frac{0.54\div30}{30\div30 min}$ = $\frac{0.08}{1 min}$ = 0.018/min Most Minutes $\frac{0.565}{30 min}$ = $\frac{0.565\div30}{30\div30 min}$ = $\frac{0.019}{1 min}$ = 0.019/min USA Card $\frac{0.55}{30 min}$ = $\frac{0.55\div30}{30\div30 min}$ = $\frac{0.018}{1 min}$ = 0.018/min

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