Question

If the mean of the first 'n'natural number is 5n/9,then find the value of n ?

Answer 1

It is given that the mean of first n natural numbers is  

9

5n

​  

.

Therefore,  

n

1+2+3+...+n

​  

=  

9

5n

​  

 

⇒  

2

n+1

​  

=  

9

5n

​  

 

⇒9n+9=10n

⇒n=9