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?
A. 9
B. 8
C. 7
D. 6
Answer:A
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?
A. 9 B. 8 C. 7 D. 6