Question

Jed is baking shortbread for a bake sale. The recipe calls for 1 1 4cups of flour and 1 2stick of butter. How many cups of flour will Jed need if he uses 3 sticks of butter?

Answer 1

Answer: $7\dfrac12$ cups of flour is required for 3 sticks of butter.

Step-by-step explanation:

We assume that quantity of flour is proportional to butter.

Given : The recipe calls of $1\dfrac14$ cups of  flour  and $\dfrac12$ stick of butter.

Let $x_1=1\dfrac14=\dfrac{5}{4}$      $y_1=\dfrac{1}{2}$

For $y_2=3$ , we will find $x_2$ by using formula of direct proportion: $\dfrac{x_1}{y_1}=\dfrac{x_2}{y_2}$

$\dfrac{\dfrac{5}{4}}{\dfrac12}=\dfrac{x_3}{3}\\\\\Rightarrow\ \dfrac{5}{2}=\dfrac{x_3}{3}\\\\\Rightarrow\ x_3=\dfrac{5}{2}\times3= \dfrac{15}2=7\dfrac12$

Hence, $7\dfrac12$ cups of flour is required for 3 sticks of butter.

Answer 2

15/2 cups of flour!