Question

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

Answer 1

Answer:

n=29

Step-by-step explanation:

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

Answer 2

Answer:

29

Step-by-step explanation:

The First natural numbers are:- 1,2,3,4,5

Their sum= 15

Mean= (n/2(n+1)) / n

15=(n+1) /2

n+1= 30

n=29

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