The average of 9 observations was 9, that of the 1st of 5 being 10 and that of the last 5 being 8. What was the 5th observation?
Q1. The average of 9 observations was 9, that of the 1st of 5 being 10 and that of the last 5 being 8. What was the 5th observation?
Answer: 9
Explanation: Sum of all 9 = 81; first 5 sum = 50; last 5 sum = 40; the 5th observation = 50 + 40 − 81 = 9.