In a red to blue ratio of 4:3, if there are 28 red objects, how many blue objects are there?

In a red to blue ratio of 4:3, if there are 28 red objects, how many blue objects are there?

• A. 14
• B. 28
• C. 21
• D. 34

Answer: (C)

Ratios express how many parts each quantity has. Here red:blue is 4:3, so red is made of four equal parts and blue of three equal parts. If red equals 28, each part is 28 ÷ 4 = 7. The blue side then has three parts, so blue = 3 × 7 = 21. You can also see this directly as blue = red × (3/4) = 28 × 0.75 = 21. A quick check: total would be 49, with red 28 (4 of 7 parts) and blue 21 (3 of 7 parts), which fits the 4:3 ratio.

Ratios express how many parts each quantity has. Here red:blue is 4:3, so red is made of four equal parts and blue of three equal parts. If red equals 28, each part is 28 ÷ 4 = 7. The blue side then has three parts, so blue = 3 × 7 = 21. You can also see this directly as blue = red × (3/4) = 28 × 0.75 = 21. A quick check: total would be 49, with red 28 (4 of 7 parts) and blue 21 (3 of 7 parts), which fits the 4:3 ratio.