If a:b = 3:9 and b:c = 9:10, then a:b:c = ? MCQ with Answer and Explanation

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If a:b = 3:9 and b:c = 9:10, then a:b:c = ?

A. 3:10:10

B. 2:9:11

C. 6:18:20

D. 3:9:10

Answer: Option D

Solution (By JKSSB Mock Tests)

Combine ratios: a:b = 3:9, b:c = 9:10 ⇒ a:b:c = 3:9:10.

This question belongs to: Maths Ratio and Proportion

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Practice More Ratio and Proportion Questions

Question #1

If a:b = 3:6 and b:c = 6:4, then a:b:c = ?

A. 3:7:4

B. 6:12:8

C. 3:6:4

D. 2:6:5

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Correct Answer: Option C

Explanation:
Combine ratios: a:b = 3:6, b:c = 6:4 ⇒ a:b:c = 3:6:4.

This question belongs to: Maths Ratio and Proportion

Question #2

If a:b = 5:7 and b:c = 7:7, then a:b:c = ?

A. 4:7:8

B. 10:14:14

C. 5:7:7

D. 5:8:7

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Correct Answer: Option C

Explanation:
Combine ratios: a:b = 5:7, b:c = 7:7 ⇒ a:b:c = 5:7:7.

This question belongs to: Maths Ratio and Proportion

Question #3

Ratio of present ages of A and B is 3:6. After 8 years, the ratio becomes 5:8. Present age of A is?

A. 138 years

B. 66 years

C. 69 years

D. 74 years

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Correct Answer: Option C

Explanation:
Let ages 3k and 6k. Then (3k + 8)/(6k + 8) = 5/8. Solving gives k ≈ 23, age of A = 3*23 = 69.

This question belongs to: Maths Ratio and Proportion

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