Question

A man bought 20 cows in rs.200000. If the average costs of 12 cows is rs.12500, what will be the average cost of remaining cows?

Answer 1

GIVEN :

A man bought 20 cows in Rs. 200000. If the average cost of 12 cows is Rs.12500, what will be the average cost of remaining cows.

TO FIND :

The average cost of remaining cows.

SOLUTION :

Given that a man bought 20 cows in Rs. 200000. And the average cost of 12 cows is Rs.12500

Let m be the total number of cows

⇒ m = 20

Let a be the cost of 1 cow

⇒ a = 10000

Let b be the cost of 12 cows

For n = 12 cows the cost  b= 12500  

If the average of m observations is 'a' and the average of n observations taken out of  is 'b', then

By using the formula

$Average of rest of the observations=\frac{(ma-nb)}{(m-n)}$

$Average cost of remaining cows = \frac{(20\times 10000 - 12\times 12500)}{(20-12)}$

$=\frac{200000-150000}{8}$

$=\frac{50000}{8}$

=6250

Average cost of remaining 8 cows =Rs. 6250