Out of three numbers, the first is twice the second and is half of the third. If the average of the three numbers is 56, then dif…

Question

Out of three numbers, the first is twice the second and is half of the third. If the average of the three numbers is 56, then difference of first and third numbers is

1. A. 12
2. B. 20
3. C. 24
4. D. 48 (Correct answer)

Correct Answer

Option D — 48

Detailed Solution & Explanation

The correct answer is 48.

Key Points

• Let the second number be x. The first is twice it, so 2x, and the first is half the third, so the third is 4x.
• Their average is 56, so (x + 2x + 4x) ÷ 3 = 56, giving 7x = 168 and x = 24.
• The numbers are 48, 24 and 96.
• Difference between the first and third = 96 − 48 = 48.

Additional Information

• Expressing all three quantities in terms of a single variable is the standard move: here the second number anchors the chain as x, 2x and 4x.
• The average condition then collapses to one equation in x, after which every number follows.
• Read the final demand carefully — the question asks for a difference between two of the numbers, not for the numbers themselves, and answering with a number rather than the difference is the usual slip.