Given that each soccer ball is bought for $5.00, so this will be the cost price.
In general, marked price is given in terms of selling price.
But since here selling price is not given, therefore it follows that here the marked price must be given with respect to the cost price itself.
Given that the price is marked 250% higher, then the marked price (MP) is given by,

Thus, the marked price on the soccer ball is $17.5