orrect answerA vendor bought bananas at 6 for a rupee. How many for a rupee must he sell to gain 20%?

The vendor bought bananas at 6 for a rupee. To gain a 20% profit, he must sell at a price that is 20% higher than his cost price.

Step 1: Calculate the cost price of one banana. The cost price of one banana = 1 rupee / 6 bananas = 0.1667 rupees per banana.

Step 2: Calculate the selling price of one banana to gain 20% profit. The selling price of one banana = cost price of one banana + 20% of cost price of one banana = 0.1667 rupees + 20% of 0.1667 rupees = 0.1667 rupees + 0.0333 rupees = 0.2 rupees per banana.

Step 3: Calculate how many bananas he must sell for a rupee to gain 20% profit. Number of bananas he must sell for a rupee = 1 rupee / selling price of one banana = 1 rupee / 0.2 rupees per banana = 5 bananas.

So, to gain a 20% profit, the vendor must sell 5 bananas for a rupee.