The sum of three numbers is 132. The first number is twice the second, and the third number is one-third of the first. Find the value of the second number.

Difficulty: Easy

Correct Answer: 36

Explanation:


Introduction / Context:
This is a classic system-of-equations problem stated in words. By expressing each relationship algebraically and using the total sum, we can solve for the second number directly and check consistency afterward.


Given Data / Assumptions:

  • Let the numbers be A (first), B (second), and C (third).
  • A + B + C = 132.
  • A = 2B.
  • C = (1/3) * A.


Concept / Approach:
Reduce to a single variable. Replace A with 2B and C with A/3 = (2B)/3 in the sum. Solve for B. Then back-substitute to verify each relation and the overall sum.


Step-by-Step Solution:

Substitute: A + B + C = 2B + B + (2B)/3.Combine: 3B + (2/3)B = (11/3)B.Set (11/3)B = 132 → B = 132 * 3 / 11 = 36.Therefore, the second number is 36.


Verification / Alternative check:
Compute A = 2B = 72 and C = A/3 = 24. Check sum: 72 + 36 + 24 = 132; all conditions hold.


Why Other Options Are Wrong:
32, 48, and 60 contradict the equation (11/3)B = 132. 24 is actually the value of C, not B.


Common Pitfalls:
Misplacing the one-third relation (e.g., taking C = 3A) or adding coefficients incorrectly when combining fractional terms.


Final Answer:
36

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