Shortcut Trick
Total SP = ₹1260 + ₹1440 = ₹2700
Total CP = 1260 × (100 ÷ 125) + 1440 × (100 ÷ 90) = ₹1008 + ₹1600 = ₹2608
Overall Gain = Total SP − Total CP = 2700 − 2608 = ₹92
Gain % = (92 ÷ 2608) × 100 = 575 ÷ 163 = 3 86/163%
∴ The correct answer is 3 86/163% Gain.
Alternate Method
Given:
Selling Price (SP) of first keyboard = ₹1260, Profit = 25%
Selling Price (SP) of second keyboard = ₹1440, Loss = 10%
Formula Used:
Cost Price (CP) = [100 ÷ (100 + Profit%)] × SP
Cost Price (CP) = [100 ÷ (100 − Loss%)] × SP
Gain % = (Gain ÷ Total CP) × 100
Calculations:
⇒ CP of first keyboard = (100 ÷ 125) × 1260 = (4 ÷ 5) × 1260 = ₹1008
⇒ CP of second keyboard = (100 ÷ 90) × 1440 = (10 ÷ 9) × 1440 = ₹1600
⇒ Total CP = 1008 + 1600 = ₹2608
⇒ Total SP = 1260 + 1440 = ₹2700
⇒ Total Gain = Total SP − Total CP = 2700 − 2608 = ₹92
⇒ Gain Percentage = (92 ÷ 2608) × 100
⇒ Gain Percentage = 9200 ÷ 2608 = 2300 ÷ 652
⇒ Gain Percentage = 575 ÷ 163 = 3 86/163%
∴ The correct answer is 3 86/163% Gain.
Additional Information
Overall Profit or Loss on Same Selling Price
When two identical items are sold at the same selling price, one at a profit of x% and the other at a loss of x%, there is always an overall loss given by Loss% = (x ÷ 10)2. In this problem, selling prices are different, so individual calculation was required.
Marked Price and Discount
Selling Price (SP) = Marked Price (MP) × (100 − Discount%) ÷ 100. This relationship is useful when the items are sold after offering a flat discount on the catalog or marked price.
Dishonest Dealer Concept
When a dealer claims to sell items at his cost price but uses a false weight, his profit percent is evaluated as: Profit % = [Error ÷ (True Value − Error)] × 100.