Three-number relation and average: The first number is twice the second and half of the third. If the average of the three numbers is 56, find the ordered triple (first, second, third).

Difficulty: Medium

Correct Answer: 48, 24, 96

Explanation:


Introduction / Context:
This problem blends proportional relationships with an average constraint. Setting variables based on the relationships simplifies solving the system.


Given Data / Assumptions:

  • First = twice the second
  • First = half of the third
  • Average of three numbers = 56


Concept / Approach:
Let the second be x. Then first = 2x and third = 4x. Use the average to find x and build the ordered triple.


Step-by-Step Solution:

Numbers: 2x, x, 4xAverage = (2x + x + 4x) / 3 = 7x / 3Set 7x / 3 = 56, so 7x = 168, x = 24First = 48, Second = 24, Third = 96


Verification / Alternative check:
Check relations: 48 is twice 24 and half of 96. Average = (48 + 24 + 96) / 3 = 168 / 3 = 56, correct.


Why Other Options Are Wrong:

  • All other permutations break at least one relation or do not average to 56.


Common Pitfalls:
Assigning inconsistent variables (e.g., mixing up which is half or double) or forgetting to apply average to three numbers.


Final Answer:
48, 24, 96

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