GIVEN:
Cost Price = Rs. 340 per litre
Label price = Rs. 408 per litre
Water as Impurity = 2/3 litre
Discount = 30%
FORMULA USED:
Profit percentage(%) = [(selling price – cost price)/cost price] × 100
CONCEPT:
When we have to calculate the profit percentage only and not the selling price, we can ignore the Cost Price
CALCULATIONS:
⇒ The trader is labelling Rs.408 on a beer whose price is Rs. 340. i.e. 68(20% of 340) rupees increasing.
⇒ Cost Price × Profit earned by labeling × profit earned by adding impurities × discount = Selling Price
⇒ 340 × (120/100) × (5/3) × (70/100) = Selling Price
⇒ 340 × 120 × 5 × 70/(100 × 3 × 100)
= 476
⇒ Profit percentage = [(476 – 340)/340] × 100 = 40%
∴ A trader will earn a 40% profit.
ALTERNATE METHOD:
Let, the COST PRICE of a beer be x.
The following operations are being made on x.
(a) labelling (b) impurities adding (iii) discount
⇒ x × ((100 + 20)/100) × ((2 + 3)/3) × ((100 - 30)/100)
⇒ x × (120/100) × (5/3) × (70/100)
⇒ x × (6/5) × (5/3) × (7/10)
⇒ x × (7/5)
= 1.40 x
⇒ Profit percentage = (1.40 – 1) × 100 = 40%
∴ A trader will earn a 40% profit.