Vendor buys bananas at 4 for Rs 3 ⇒ cost price of 1 banana = Rs. 3/4 Vendor sells bananas at 3 for Rs 4 ⇒ selling price of 1 banana = Rs. 4/3 We see that selling price is more than the cost price which implies there is a profit. Profit % = [(4/3 - 3/4)/3/4] × 100 = 77.7% ∴ There is profit of 77.7%