Question

The mean of first n natural numbers is 5n/9.then n is?

Answer 1

Hi ,

mean of first n natural numbers

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

according to the problem given ,

mean of first n natural numbers = 5n/9 ---( 2 )

Therefore ,

( 1 ) = ( 2 )

( n + 1 ) / 2 = 5n/9

( n + 1 )/2 = 5n/9

9( n + 1 ) = 5n × 2

9n + 9 = 10n

9 = 10n - 9n

9 = n

n = 9

I hope this helps you.

: )

Answer 2

HEY!!

_______________________________

We know that mean of first n natural numbers is 
$\frac{n + 1}{2}$
$\frac{5n}{9} = \frac{n + 1}{2}$
✔10n=9n+9

▶▶n=9