Question

Honey's blueberry muffin recipe calls for 3 1/4 pounds of blueberries and 2 1/2 cups of muffin mix. How many cups of muffin mix should Honey use if she plans to use 7 pounds of blueberries. Answer and explain briefly.

Answer 1

For this case we convert the mixed numbers to improper fractions:
`3 \frac {1} {4} = \frac {4 * 3 + 1} {4} = \frac {12 + 1} {4} = \frac {13} {4}\\2 \frac {1} {2} = \frac {2 * 2 + 1} {2} = \frac {4 + 1} {2} = \frac {5} {2}`

Now, we propose a rule of three:

`\frac {13} {4}`pounds of blueberries ------------->
`\frac {5} {2}`cups of muffin mix

7 pounds of blueberries -----------------------------> x

Where the variable "x" represents the number of cups of muffin mix that Honey should use.

`x = \frac {7 * \frac {5} {2}} {\frac {13} {4}}\\x = \frac {\frac {35} {2}} {\frac {13} {4}}\\x = \frac {35 * 4} {2 * 13}\\x = \frac {140} {26}\\x = \frac {70} {13}\\x = 5.38`

So approximately Honey should use
`5 \frac {5} {13}` cups of muffin mix

Answer:

Approximately Honey should use
`5 \frac {5} {13}` cups of muffin mix