Question

If the mean of first n natural numbers is 3n/5, then the value of n is

Answer 1

Answer:

n(n+1)/2=3n/5

n^2+n/2=3n/5

n^2+n=2(3n/5)

n^2+n=6n/5

5n^2+5n=6n

5n^2+5n-6n=0

5n^2-n=0

find factors u will get n value