Question

# The average of 5 observations is 12. If the average of the first 3 observations is 10, then find the average of the other two.

A
10
B
12
C
15
D
12.5

Solution

## The correct option is C 15Let us suppose that the value of 5 observations is a , b, c, d, e. Now average of 5 observations can be represented as a+b+c+d+e5=12 . Hence, a+b+c+d+e = 60.....(i) . It is also given that the average of the first three observations is 10 ⇒  a+b+c3=10. ⇒  a+b+c =30...........(ii) From (i) and (ii) we get d + e = 30. Hence, the average of the other two observations i.e. 'd' and 'e' is d+e2=15Mathematics

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