On a particular transaction, a shopkeeper earns 400% on cost. If the cost rises by 100% and the selling price remains unchanged, the ratio between the new profit and the selling price is:

3 : 5

Let the cost price = 100

Earnings = 400%

Then the selling price = 500

According to the question,

           CP                    SP

Old     100                  500

New    200                 500

New profit = 500 - 200 = 300

New profit : Selling Price = 300 : 500 = 3 : 5