average

        If the average of m numbers is a, and on adding x to the m numbers, the average of the (1+m) numbers is b. Then find the value of x.?

Answer:

Let the sum of m numbers be S

So, S = ma

Also, S + x = (m + 1).b

Therefore, on substituting (1) in (2), we get

Or, ma + x = (m +1).b

Or, x = (m +1).b – ma

Or, x =  m(b – a) + b