Difficulty: Medium
Correct Answer: 36
Explanation:
Introduction / Context:
Given averages for the whole and a subset, we can compute the total of the remaining items. With a ratio for those two items, convert the total to parts and extract each number.
Given Data / Assumptions:
Concept / Approach:
Sum of the remaining two = T − S. If they are 2k and 3k, then 5k equals that sum; solve k to get both, then choose the smaller (2k).
Step-by-Step Solution:
Verification / Alternative check:
Other number = 54; together 36 + 54 = 90. Totals reassemble correctly: 306 + 90 = 396 ⇒ average 36.
Why Other Options Are Wrong:
18, 54, 48: Do not match the ratio and total simultaneously. 36 is the unique smaller value.
Common Pitfalls:
Dividing 90 by 2 (getting 45, 45) and ignoring the 2 : 3 ratio, or picking the larger number by mistake.
Final Answer:
36
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