A wholesaler sells a box of chocolates at Rs 960 and gains 20% on his cost price. If he decides instead to sell the same box at Rs 1120, what will be his profit percentage?

Introduction / Context:
This profit and loss question asks you to find a new profit percentage when the selling price changes but the cost price remains the same. The wholesaler initially sells at one price with a known profit percentage and then changes the selling price. The task is to recompute the profit percentage using the unchanged cost and new selling price. These types of questions are very common in aptitude exams and test basic comfort with reverse percentage calculations.

Given Data / Assumptions:

• First selling price SP1 = Rs 960 with 20% profit.
• Second selling price SP2 = Rs 1120.
• Cost price CP is the same in both situations.
• We need to find profit percentage at SP2.

Concept / Approach:
First reconstruct the cost price from the initial selling price and profit percentage. Profit of 20% means selling price equals 120% of cost price. So CP can be found by dividing SP1 by 1.20. Once CP is known, profit at the new selling price is simply SP2 minus CP. Finally the profit percentage is calculated as (Profit / CP) * 100. This two stage process is standard in profit and loss problems with changed selling price.

Step-by-Step Solution:
Step 1: Let CP be cost price.Step 2: SP1 = Rs 960 corresponds to a profit of 20%.Step 3: Therefore SP1 = 120% of CP = 1.20 * CP.Step 4: So CP = 960 / 1.20 = Rs 800.Step 5: Now consider the new selling price SP2 = Rs 1120.Step 6: Profit at SP2 = SP2 - CP = 1120 - 800 = Rs 320.Step 7: Profit percentage = (320 / 800) * 100 = 40%.Step 8: Therefore the wholesaler makes 40% profit at the new selling price.

Verification / Alternative check:
We can check consistency by looking at the ratio of selling price to cost price at SP2. If CP is 800 and SP2 is 1120, then SP2 / CP = 1120 / 800 = 1.4. This means the selling price is 140% of the cost price, which implies a profit of 40%. This ratio check matches the earlier arithmetic and confirms the correctness of the answer.

Why Other Options Are Wrong:
Option A (30) would imply a selling price of only 130% of cost price, that is 1040 if CP is 800, which does not match the given 1120. Option C (50) would require SP to be 150% of CP or 1200, again not matching. Option D (60) would correspond to 160% of CP or 1280, which is also incorrect. Only option B, 40, matches the profit percentage deduced from the given SP2 of 1120 and CP of 800.

Common Pitfalls:
Sometimes students mistakenly apply the new profit percentage directly on the original selling price or confuse which base to use for percentage calculation. Another error is to assume the profit increases by the same absolute number of percentage points as the increase in selling price, which is not generally true. Always reconstruct the cost price first when one profit percentage and selling price pair is given, then recompute any new profit or loss percentages from that fixed cost price.

Final Answer:
At a selling price of Rs 1120, the wholesaler makes a 40 percent profit.