DRDO Multi tasking staff Model paper 4

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%