A trader mixes 15 kg of rice at ₹ 15 per kg with 10 kg of rice of other variety at ₹ 12.5 per kg and sells the mixture at ₹ 21 per kg. Find the profit percent. 

Given:

Weight of first variety of rice = 15 kg

Cost of first variety of rice = ₹ 15 per kg

Weight of second variety of rice = 10 kg

Cost of second variety of rice = ₹ 12.5 per kg

Selling price of the mixture = ₹ 21 per kg

Formula Used:

Cost price (CP) of mixture = (Weight of first variety × Cost of first variety + Weight of second variety × Cost of second variety) / Total weight

Profit percent = ((Selling price - Cost price) / Cost price) × 100

Calculation:

CP of mixture = (15 × 15 + 10 × 12.5) / (15 + 10)

⇒ CP of mixture = (225 + 125) / 25

⇒ CP of mixture = 350 / 25

⇒ CP of mixture = 14

Selling price (SP) = ₹ 21 per kg

Profit percent = ((21 - 14) / 14) × 100

⇒ Profit percent = (7 / 14) × 100

⇒ Profit percent = 0.5 × 100

⇒ Profit percent = 50%

The profit percent is 50%.