Thinking Mathematically (6th Edition)

Published by Pearson
ISBN 10: 0321867327
ISBN 13: 978-0-32186-732-2

Chapter 5 - Number Theory and the Real Number System - 5.3 The Rational Numbers - Exercise Set 5.3 - Page 286: 128


1 cup of sugar will make 10 whole brownies.

Work Step by Step

It takes 1$\frac{1}{2}$ cups of sugar to make 16 brownies. So, we can find the number of brownies to be made with 1 cup of sugar by dividing 16 by 1$\frac{1}{2}$. To complete this division, we must first convert the mixed numeral, 1$\frac{1}{2}$ to $\frac{3}{2}$. We also must write 16 has a fraction. This can be accomplished by writing it over 1 (see below). For fraction division, we keep the first fraction as it is. We flip the second fraction over (this is called finding the reciprocal), and we change the operation from division to multiplication. Now, $\frac{16}{1}$ $\div$ $\frac{3}{2}$ is $\frac{16}{1}$ x $\frac{2}{3}$ = $\frac{32}{3}$ = 10$\frac{2}{3}$ Since the instructions state to ignore fractional parts and only count the whole numbers, we can make 10 whole brownies.
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