Question

(0) All of these
21. The number of observations in a group is 50. If the average of first 20 is 5 and that of the remaining 30 is 4,then the average of the whole group is:
(a) 4.1
(b) 4
(d) 4.4
(d)4.2​

Answer 1

Answer:

..........d.

4.2......,..

Answer 2

Answer:

n= 50

n1= 20, x1= 5

n2= 30 ,x2= 4

Mean= sum of observations/ total no. of observations

sum of 20 observations = n1x1 = 20×5 = 100

sum of 30 observations = n2x2 = 30×4 = 120

Average of whole group= n1x1 + n2x2 / n

= 100+120 / 50

= 220/50

= 4.4

Answer (d) is correct.