Average of six numbers comes out to be 3.95. Average of two of the numbers is…
2025
Average of six numbers comes out to be 3.95. Average of two of the numbers is 3.4 while the average of other two is 3.85. Determine the average of the two numbers left.
- A.
4.7
- B.
4.8
- C.
4.3
- D.
4.6
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Correct answer: D
Key idea: work with sums rather than averages.
Total sum of the six numbers = 6 × 3.95 = 23.7.
Sum of the two numbers with average 3.4 = 2 × 3.4 = 6.8.
Sum of the two numbers with average 3.85 = 2 × 3.85 = 7.7.
Sum of the remaining two numbers = 23.7 − 6.8 − 7.7 = 9.2.
Average of the remaining two = 9.2 ÷ 2 = 4.6.
Alternate quick method: since each given average is over two numbers, the overall average equals the average of the three pair-averages: 3.95 = (3.4 + 3.85 + x)/3, which gives x = 4.6.
Answer: 4.6