A sweet shop owner buys 10 boxes of sweets for the price of 8 boxes from a wholesaler. If he sells each box at a 2% discount on its marked price, what is his profit percentage?

Correct option is C

Given:

He buys 10 boxes for the price of 8 boxes.
He sells each box at a 2% discount on its marked price.

Formula Used:
Profit = Selling Price (SP) − Cost Price (CP).
Profit percentage =$$\dfrac{\text{Profit}}{\text{CP}}\times100$$​​

Solution:
Let marked price (MP) of one box = M

Total cost for 10 boxes =8M (pays for 8 boxes).
​$$\text{CP per box}=\frac{8M}{10}=0.8$$​M
Selling price per box after 2% discount:
​$$\text{SP per box}=M(1-0.02)=0.98M$$​​
Profit per box:
Profit = SP - CP = 0.98M - 0.8M = 0.18M
Profit% =$$\frac{0.18M}{0.8M}\times100=\frac{0.18}{0.8}\times100$$​​
= 22.5%