It will be 13.04% on cost

suppose the selling price is 100, then the profit will be 100*15% i.e. 15

and the cost will be 100-15 = 85

so the profit on cost will be 15/85*100=  17.65%

17.65%

Dont understand why this Question (multiple choice) by Jyoti

Always remember this golden rule

1/X ON cost = 1/x+1 on sales

Profit on Cost will obviously be more than profit on sales applying common sense, unless you are selling a product less that its cost, in that case it will be loss and not profit