On selling 17 balls at Rs. 720, there is a loss equal to the cost price 0f 5 balls. The cost price of a ball is:

1. A) 45
2. B) 50
3. C) 65
4. D) 60

Solution :

Let the cost price of a ball be X.

C.P of 17 balls is 17 x.

C.P of 5 balls is 5 x.

Loss = C.P – S.P

5x = 17x -720

17x = 5x – 720

17 x – 5x = 720

12x = 720

X= 720/12

X= 60

Cost price of a ball is 60.