A fruit vendor buys 12 bananas for Rs 60 and later sells 5 bananas for Rs 32. What percentage gain does the vendor make on his overall transaction?

Introduction / Context:
This is a basic profit and loss question involving unit cost and unit selling price. Such questions are very common in aptitude exams because they test whether a learner understands how to compare cost price and selling price when the items are sold in different group sizes. Here, a fruit vendor buys bananas in one batch and sells them in another, and we have to compute the percentage gain on the overall transaction.

Given Data / Assumptions:
- The vendor buys 12 bananas for Rs 60. - The vendor sells 5 bananas for Rs 32. - All bananas are assumed to be of equal quality and size. - We assume no wastage or leftover bananas.

Concept / Approach:
Profit or loss percentage is always calculated on cost price. First we find the cost price per banana, then the selling price per banana, and then compare them. The basic formulas used are:
profit = selling price - cost price profit percent = (profit / cost price) * 100 When the number of items is the same, it is convenient to compare per unit prices.

Step-by-Step Solution:
Step 1: Cost price of 12 bananas = Rs 60. Step 2: Cost price per banana = 60 / 12 = Rs 5. Step 3: Selling price of 5 bananas = Rs 32. Step 4: Selling price per banana = 32 / 5 = Rs 6.4. Step 5: Profit per banana = 6.4 - 5 = Rs 1.4. Step 6: Profit percent = (1.4 / 5) * 100 = 28%.

Verification / Alternative check:
We can also consider a common multiple of bananas, for example 60 bananas. Cost price for 60 bananas = 60 * 5 = Rs 300. Selling price for 60 bananas = 60 * 6.4 = Rs 384. Profit = 384 - 300 = Rs 84. Profit percent = (84 / 300) * 100 = 28%. This confirms the earlier calculation.

Why Other Options Are Wrong:
Option 32 gives a higher gain than the correct value and would correspond to a larger selling price per banana than actually given. Option 24 underestimates the gain and would arise if someone used an incorrect cost base. Option 22 also understates the gain and could come from rounding or using 6.2 instead of 6.4 as selling price per banana.

Common Pitfalls:
A frequent mistake is to compare 60 and 32 directly without converting to per banana values. Another pitfall is to treat 60 and 32 as profit and cost, which is incorrect, or to divide by the wrong number of bananas. Learners should remember that profit percentage must always be compared to cost price, not selling price.

Final Answer:
The vendor makes a profit of 28% on the transaction.