Quantitative Aptitude • Ratio, Average & MixtureHard
The average of 9 results is 47. The average of the first 5 results is 53 and the average of the last 5 results is 51. What is the 5th result?
A. 52
B. 47
C. 144
D. 97✓ Correct Answer
💡 Solution & Explanation
The first 5 and the last 5 results together make 10 results, but there are only 9: the 5th result is counted in both groups. Sum of the first 5 = 5 × 53 = 265; sum of the last 5 = 5 × 51 = 255; sum of all 9 = 9 × 47 = 423. So the 5th result = 265 + 255 − 423 = 97.
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