The ratio of the ages of A and B is 5:7. After 10 years, the ratio will be 7:9. Find the present age of A. MCQ with Answer and Explanation

The ratio of the ages of A and B is 5:7. After 10 years, the ratio will be 7:9. Find the present age of A.

A. 25 years

B. 35 years

C. 30 years

D. 20 years

Answer: Option A

Let ages 5x, 7x. (5x+10)/(7x+10) = 7/9 → 45x+90 = 49x+70 → 4x=20 → x=5, A=25.

This question belongs to: Maths Percentage

No comments yet. Be the first to start the discussion!

Question #1 Report Error

The price of an item increases by 25% and then decreases by 20%. What is the net percentage change?

A. 10% increase

B. 5% increase

C. 0%

D. 5% decrease

Correct Answer: Option C

Explanation:
Net change = 25 - 20 + ((25 * -20) / 100) = 5 - 5 = 0%.

This question belongs to: Maths Percentage

Question #2 Report Error

A number is increased by 10%, then increased by 20%, then decreased by 10%. Net percentage change:

A. 12.8% increase

B. 20% increase

C. 16% increase

D. 18.8% increase

Correct Answer: Option D

Explanation:
1.1 × 1.2 × 0.9 = 1.188, increase 18.8%.

This question belongs to: Maths Percentage

Question #3 Report Error

A student multiplied a number by 4/5 instead of 5/4. What is the percentage error?

A. 45%

B. 25%

C. 36%

D. 30%

Correct Answer: Option C

Explanation:
Error = (5/4 - 4/5)x = (9/20)x. % Error = ((9/20) / (5/4)) * 100 = (9/25) * 100 = 36%.

This question belongs to: Maths Percentage