Bihar Police Constable Model Paper 1

Formula used :
Selling Price = Cost Price + Profit
Calculations :
Cost price of 25 books = Cost price of 20 books + Profit on 20 books
⇒ Cost of Price of 25 books – Cost price of 20 books = Profit on 20 books
⇒ Profit on 20 books = Cost price of 25 books – Cost price of 20 books
⇒ Profit on 20 books = Cost price of 5 books.
Thus,
Profit percentage = [Cost price of 5 books/Cost price of 20 books] × 100 = (5/20) ×100 = 25%