Find the mean proportional between 7 and 9. MCQ with Answer and Explanation

Find the mean proportional between 7 and 9.

A. 7

B. 14

C. 10

D. 16

Answer: Option A

Mean proportional = √(7 × 9) = √(63) = 7.

This question belongs to: Maths Ratio and Proportion

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Question #1 Report Error

Ratio of present ages of A and B is 4:7. After 11 years, the ratio becomes 5:8. Present age of A is?

A. 80 years

B. 45 years

C. 40 years

D. 36 years

Correct Answer: Option C

Explanation:
Let ages 4k and 7k. Then (4k + 11)/(7k + 11) = 5/8. Solving gives k ≈ 10, age of A = 4*10 = 40.

This question belongs to: Maths Ratio and Proportion

Question #2 Report Error

If a:b = 3:8 and b:c = 8:8, then a:b:c = ?

A. 6:16:16

B. 3:8:8

C. 2:8:9

D. 3:9:8

Correct Answer: Option B

Explanation:
Combine ratios: a:b = 3:8, b:c = 8:8 ⇒ a:b:c = 3:8:8.

This question belongs to: Maths Ratio and Proportion

Question #3 Report Error

If a:b = 2:7 and b:c = 7:9, then a:b:c = ?

A. 1:7:10

B. 2:8:9

C. 2:7:9

D. 4:14:18

Correct Answer: Option C

Explanation:
Combine ratios: a:b = 2:7, b:c = 7:9 ⇒ a:b:c = 2:7:9.

This question belongs to: Maths Ratio and Proportion