Question

14. Cost price of 10 pens is equal to the selling price of 9
pens.. Calculate the profit per cent
​

Answer 1

Solution:

Let

CP of 10 pens=x

CP of 1 pen=x/10

And, SP of 9 pens=x

SP of 1 pen=x/9

Here x/9>x/10

Therefore profit.

Profit=x/9-x/10

= 10x-9x/90

= x/90

Profit %=x/90/x/10×100 %

= 11.11 %