Normally commercial milk should be sold at Rs 36/liter which contains 90% milk and 10% water. A milkman who dishonestly sells 80% milk mixture as commercial milk in a cylindrical vessel that is supposed to be 5 cm in radius and 7 cm tall. The vessel is also tampered that the radius is reduced to 4 cm. If he sold the milk, he would have got 20% profit. What is the profit (in %) he obtained after cheating?
Normally commercial milk should be sold at Rs 36/liter which contains 90% milk and 10% water. A milkman who dishonestly sells 80% milk mixture as commercial milk in a cylindrical vessel that is supposed to be 5 cm in radius and 7 cm tall. The vessel is also tampered that the radius is reduced to 4 cm. If he sold the milk, he would have got 20% profit. What is the profit (in %) he obtained after cheating? Correct Answer 4 7/16
By selling dishonestly he would have got 20% profit
Cost price for 90% milk = 36 × 100/ (100 + profit%)
⇒ 36 × 100/(100 + 20)
⇒ Rs. 30
Cost of 80% milk = 30/9 × 8
⇒ Rs. 80/3
Volume of original vessel = π r2 h
⇒ 22/7 × 52 × 7
⇒ 550 cm3
Volume of tampered vessel = 22/7 × 42 × 7
⇒ 352 cm3
∴ Profit% = (Selling price of 550 cm3 – Cost price of 352 cm3)/(Cost price of 352 cm3) × 100
⇒ (550 × 36/1000 – 80/3 × 352/1000)/(80/3 × 352/1000) × 100
⇒ (781/75)/(704/3) × 100
⇒ 4 7/16%