70% of a number is 28 less than 90%. Number is: MCQ with Answer and Explanation

70% of a number is 28 less than 90%. Number is:

A. 120

B. 140

C. 150

D. 130

Answer: Option B

0.9x - 0.7x = 28 → 0.2x = 28 → x = 140.

This question belongs to: Maths Percentage

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Question #1 Report Error

Price of a commodity falls by 15%. To keep expenditure constant, consumption must increase by:

A. 20%

B. 18%

C. 15%

D. 17.64%

Correct Answer: Option D

Explanation:
New price 0.85, consumption multiplier needed = 1/0.85 ≈ 1.17647, increase 17.64%.

This question belongs to: Maths Percentage

Question #2 Report Error

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. 20 years

C. 30 years

D. 35 years

Correct Answer: Option A

Explanation:
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

Question #3 Report Error

50% of 500 minus a number gives 200. The number:

A. 55

B. 50

C. 45

D. 40

Correct Answer: Option B

Explanation:
250 - x = 200 → x = 50.

This question belongs to: Maths Percentage