Question

A certain shade of pink is creating by adding 3 cups of red paint to 7 cups of white paint

Answer 1

A certain shade of pink is creating by adding 3 cups of red paint to 7 cups of white paint.

Since, 7 cups of white paint are added with 3 cups of red paint.

We have to determine that how many cups of red paint should be added to the paint when 1 cup of white paint is being added.

We will use unitary method to solve this problem.

So, 1 cup of white paint should be added with $\frac{3}{7}$ cup of red paint to create pink paint.

Therefore,  $\frac{3}{7}$ cup of red paint is added with 1 cup of white paint.

Answer 2

Given that a certain shade of pink is created by adding 3 cups of red paint with 7 cups of white paint.

That means ratio of red paint and white paint must 3:7 .

Let x be the amount of red paint cups for 1 cup of white paint.

Then ratio of red paint to white paint is $\frac{x}{1} = \frac{3}{7}$

                                                                      $x = \frac{3}{7}$

Hence $\frac{3}{7}$ cups of red paint is needed for 1 cup of white paint.

The number in "?" is  $\frac{3}{7} cups$ or 0.04286 cups.