Question

The average of some natural numbers is 15. If
30 is added in first number and 5 is subtracted
from last number then average becomes 17.5.
How many natural numbers are there?
(1) 30 (2) 20 (3) 15 (4) 10​

Answer 1

Answer:

10

Step-by-step explanation:

Let,

There be n natural numbers

Given,

Average of n numbers = 15

We know that,

Average=Sum of all numbers/Total numbers

Sum of n numbers/n=15

Sum of n numbers = 15n ---------------(1)

Now,

{Sum of numbers +30-5}/n=17.5

By using eq(1)

15n+25=17.5n

25=2.5n

10=n

Therefore there are 10 natural numbers