Question

A mixture of paint calls for 1/3 cups of red paint and 3/4 cups of yellow paint. If there were 4 cups of red paint added to the mixture, how many cups of yellow paint would need to be added to keep a constant rate of proportionality? (Hint: You can use your answer from the first question to help you solve this!)

Answer 1

9 cups of yellow paint

Explanation:

A mixture of paint calls for 1/3 cups of red paint and 3/4 cups of yellow paint.

From the above question

1/3 cups of red paint = 3/4 cups of yellow paint

1 cup of red paint = x cups of yellow paint

Cross Multiply

1/3 × x = 3/4 × 1

x = 3/4 ÷ 1/3

x = 3/4 × 3/1

x = 9/4

x = 2 1/4 cups of yellow paint

Hence, 1 cups of red paint requires 2 1/4 cups of yellow paint

If there were 4 cups of red paint added to the mixture, how many cups of yellow paint would need to be added to keep a constant rate of proportionality?

1 cups of red paint = 2 1/4 cups of yellow paint

4 cups of red paint = x cups of yellow paint

Cross Multiply

x cups of yellow paint = 4 × 2 1/4 cups of yellow paint

= 4 × 9/4 cups of yellow paint

= 9 cups of yellow paint

Therefore, 4 cups of red paint requires 9 cups of yellow paint