Blue and yellow paints are mixed in the ratio of 3 : 5 to produce green paint. To produce 40 mL of green paint, how much of these two colours are needed? To make the paint a lighter shade of green, I added 20 mL of yellow to the mixture. What is the new ratio of blue and yellow in the paint?

Question

Bright Tutorials · Accepted Answer

Ratio of blue and yellow paints = 3 : 5
Quantity of green paint = 40 mL
∴ Quantity of blue paint = $\frac{3}{3+5} \times 40$
= $\frac {3}{8}$ × 40
= 15 mL
∴ Quantity of yellow paint = $\frac{5}{3+5} \times 40$
= $\frac {5}{8}$ × 40
= 25 mL
Addition of yellow paint to the mixture = 20 mL
∴ New quantity of blue paint = 15 mL
∴ New quantity of yellow paint = 25 mL + 20 mL = 45 mL
∴ New ratio of blue and yellow paints = 15 : 45 = 1 : 3.

Proportional Reasoning 1 — Question 3