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.
The correct option is C 15
Let 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