Question

If the mean of the first n natural number is 15, then find n.

Answer 1

Given: 1, 2, 3, 4, ... to n terms.

∴ The sum of first n natural numbers = `(n(n + 1))/2`

So, mean = `(n(n + 1))/(2 xx n)`

⇒ `(n + 1)/2 = 15`

⇒ n + 1 = 30

⇒ n = 29