A shopkeeper expects a gain of 22.5% on his cost price. If in a week, his sale was of Rs. 392, what was his profit?

Given Data

• Expected profit on cost = 22.5%
• Total weekly sales (SP) = Rs. 392
• Required: profit in rupees

Step 1: Relate SP and CP via profit on cost
SP = CP × (1 + 22.5%) = 1.225 × CP392 = 1.225 × CP ⇒ CP = 392 ÷ 1.225 = Rs. 320

Step 2: Compute profit
Profit = SP − CP = 392 − 320 = Rs. 72

Checks & Common Pitfalls

• 22.5% on cost means multiply CP by 1.225 to obtain SP.
• Do not treat 22.5% as on selling price; the base matters.

Final Answer
Weekly profit = Rs. 72.