Question

A distribution consists of three groups having 40, 50 and 60 items with means 20, 26 and 15 respectively. The

mean of the distribution is:
A)25
B)18
C)22
D)20​

Answer 1

20 is the ans
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Answer 2

Answer:

f1 = 45 , f2 = 50 and f3 = 60

x1 =20 , x2 =26 and x3 = 15

= f1 x X1 + f2 x X2 + f3 x X3 / f1 + f2 + f3

= 45x20 + 50 x26 + 60x15 / 45+50+60

= 900+1300+900/155

= 20 ans