The mean of 20 observation is 19. One more observation is included and the new mean becomes 20. The 21st observation is:
A. 20
B. 30
C. 40
D. 42
1
C
2
D
3
B
4
A
The mean of 20 observation is 19. One more observation is included and the new mean becomes 20. The 21st observation is:
A. 20
B. 30
C. 40
D. 42