On selling 17 balls at Rs. 720, there is a loss equal to the cost price of 5 balls. The cost price of a ball is:
Rs. 45
Rs. 50
Rs. 55
Rs. 60
Explanation:
[C.P. of 17 balls] - [S.P. of 17 balls] = [C.P. of 5 balls]
$\Rightarrow$ C.P. of 12 balls = S.P. of 17 balls = Rs.720.
$\Rightarrow$ C.P. of 1 ball = Rs.$ \left(\dfrac{720}{12} \right) $= Rs. 60.