Basic College Mathematics (10th Edition)

Published by Pearson
ISBN 10:
ISBN 13:

Chapter 3 - Adding and Subtracting Fractions - 3.4 Adding and Subtracting Mixed Numbers - 3.4 Exercises - Page 228: 28

Answer

Estimated answer = 9 Exact answer = $9\frac{9}{40}$

Work Step by Step

$15\frac{7}{20}$ - $6\frac{1}{8}$ Estimation: $15\frac{7}{20} \approx 15$ $6\frac{1}{8} \approx 6$ Therefore $15\frac{7}{20}$ - $6\frac{1}{8}$ $\approx$ 15 - 6 = 9 Exact Calculation: $15\frac{7}{20}$ - $6\frac{1}{8}$ = $15\frac{7\times2}{20\times2}$ - $6\frac{1\times5}{8\times5}$ (40 is the least common denominator) = $15\frac{14}{40}$ - $6\frac{5}{40}$ = $15$ + $\frac{14}{40}$ - ($6$ + $\frac{5}{40})$ = $15$ + $\frac{14}{40}$ - $6$ - $\frac{5}{40}$ = ($15$ - $6$) + ($\frac{14}{40}$ - $\frac{5}{40}$) (Solving whole parts separately and fractional parts separately) = $9$ + $\frac{14 - 5}{40}$ = $9$ + $\frac{9}{40}$ = $9\frac{9}{40}$ The estimate was 9, so the exact answer of $9\frac{9}{40}$ is reasonable.
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.