The centralville high school cooking club has 12 1/2 pounds of flour with which to make tortillas, there are 3 3/4 cubs of flour in one pound, and it takes about 1/3 cup of flour per tortilla, how many tortillas can they make?

Jun 19, 2018

140

Explanation:

Given conversion ratio is:
1^("lb")color(white)("d") :color(white)("d")3 3/4" cups"

But the clube has $12 \frac{1}{2} {\textcolor{w h i t e}{}}^{\text{lb}}$ of flour. Thus to change the pounds in the ratio to match the amount available multiply everything in the ratio by $12 \frac{1}{2}$

12 1/2 (1^("lb")color(white)("d") :color(white)("d")3 3/4" cups")color(white)("d")-> 12 1/2 color(white)()^("lb")color(white)("d") :color(white)("d")46 7/8" cups"

Now we knoe the amount of flour available is $46 \frac{7}{8} \text{cups}$

Each tortilla takes $\frac{1}{3}$ cups so the count of tortillas is
$\left(46 \frac{7}{8} \cancel{\text{cups"))/(1/3 cancel("cups}}\right) = 46 \frac{7}{8} \times 3 = 140 \frac{5}{8}$

You can not make part of a tortilla so the final count is 140