Quantitative Aptitude • Ratio, Average & MixtureHard
The average of 13 results is 39. The average of the first 7 results is 45 and the average of the last 7 results is 41. What is the 7th result?
A. 134
B. 95✓ Correct Answer
C. 43
D. 39
💡 Solution & Explanation
The first 7 and the last 7 results together make 14 results, but there are only 13: the 7th result is counted in both groups. Sum of the first 7 = 7 × 45 = 315; sum of the last 7 = 7 × 41 = 287; sum of all 13 = 13 × 39 = 507. So the 7th result = 315 + 287 − 507 = 95.
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