Question

if the mean of first natural
nos is 15 them


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Answer 1

Answer:

The first n natural numbers are 1,2,3,...,n

Given that mean of n natural numbers is 15

⟹

n

1+2+3+...+n

=15 ———(1)

We know that sum of first n natural numbers is

2

n(n+1)

⟹1+2+3+...+n=

2

n(n+1)

———(2)

Substituting (2) in (1) we get

⟹

2n

n(n+1)

=15

⟹n+1=30⟹n=30−1=29