Question

22. The mean age of 40 students is 16 years and the mean
age of another group of 60 students is 20 years. Find
out the mean age of all the 100 students combined
together:
(A) 18.4
(B) 19
(C) 19.6
(D) 20​

Answer 1

here it is given that

mean age of 40 students is 16 thus,

sum of observations

——————————— = mean

no. of students

sum of observations

———————————= 16.

40

sum of observations = 16×40. = 640

for the other group

sum of observations.

——————————— = mean

no. of students

sum of observations

——————————— = 20

60

sum of observations = 20 ×60 = 1200

mean age of all the hundred students

= sum of observations of the first group + sum of observations of second group

—————————————————————————

no. of students

=. 640+1200. 1840.

———————. = ———— = 18.4

100. 100