Question

A cake recipe requires 3 and 1/4 cups of flour for 13 servings and 4 and 1/2 cups of flour for 18 servings. How much flour is required to make a cake that serves 28?

Answer 1

So, each serving requires:

3 1/4 divided into 13:
$3\frac{1}{4} /13= \frac{13}{4} * \frac{1}{13} = \frac{1}{4}$

let's check from the second information:
4 2/4 divided into 18:
$4\frac{2}{4} /18= \frac{18}{4} * \frac{1}{18} = \frac{1}{4}$


so for 28, we need:

$\frac{1}{4} *28= \frac{28}{4} = \frac{14}{2} = 7$

we need 7 cups of flour!