Question

Mary mixes white paint and blue paint in the ratio 2:3

She makes a total of 20 litres of paint.

How much more blue paint does she need to add to the mixture so that the ratio of white paint to blue paint becomes 1:7?

Answer 1

Given:

Ratio of white and blue paint is 2:3

Total quantity of paint is 20 litres

To find:

Quantity of blue paint to be mixed so that the ratio of white paint to blue paint becomes 1:7

Solution:

The ratio 2:3 totals 20 that is
`2x+3x=20\rightarrow5x=20\rightarrow x=4`

So, the quantity of white paint in the mixture is
`2*4=8` and the quantity of blue paint in the mixture is
`3*4=12`

Now, to get the final ratio as 1:7, Mary should have
`7*8=56 \text{ litres }` of blue paint. So, she need to add
`56-12=44 \text{ litres}`.

Therefore, Mary has to add 44 litres of blue paint to the mixture to make the ratio as 1:7.