Quantitative Aptitude • Ratio, Average & MixtureHard
The average of 7 results is 51. The average of the first 4 results is 51 and the average of the last 4 results is 53. What is the 4th result?
A. 52
B. 51
C. 59✓ Correct Answer
D. 110
💡 Solution & Explanation
The first 4 and the last 4 results together make 8 results, but there are only 7: the 4th result is counted in both groups. Sum of the first 4 = 4 × 51 = 204; sum of the last 4 = 4 × 53 = 212; sum of all 7 = 7 × 51 = 357. So the 4th result = 204 + 212 − 357 = 59.
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