Precalculus (6th Edition)

Published by Pearson
ISBN 10: 013421742X
ISBN 13: 978-0-13421-742-0

Chapter R - Review of Basic Concepts - R.5 Rational Expressions - R.5 Exercises - Page 55: 90


\approx 2305 miles

Work Step by Step

This problem can be solved using the formula given in the problem: Distance = \frac{7-x}{0.639x + 1.75}. Since the question asks about the distance of a river that has an altitude of 1200 ft, convert the 1200 ft into thousands of feet for the variable x by dividing 1200 by 1000. Therefore, x = 1.2. Now, substitute 1.2 for x into the formula, which gives the expression: \frac{7 - 1.2}{0.639(1.2) + 1.75} Next, simplify the expression, and get the distance. \frac{7 - 1.2}{0.639(1.2) + 1.75} = \frac{5.8}{0.7668 + 1.75} = \frac{5.8}{2.5168} \approx 2.3045 Then, multiply 2.3045 by 1000, which gives 2304.5 miles. Since the question asks about the nearest mile, round 2304.5 into 2305 miles. As a result, the distance from the origin of the Nile when the river has an altitude of 1200 ft is around 2305 miles.
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