How much rice worth price Rs. 12.85 per kg be mixed with 25 kg of rice worth Rs. 14.80 per kg so as to when they sell the rice at Rs. 16 per kg, they get profit of 15% on selling price?

A 30 kg

B 35 kg

C 40 kg

D 45 kg

E None of these

Correct Answer: Option C

Let x kg of rice worth Rs. 12.85 per kg be mixed.

Now total cost of this ‘x’ kg of rice = 12.85x

∴ Total cost of mixture = (14.80 × 25) + 12.85x = 370 + 12.85x

∵The trader will sell the mixture at Rs. 16 per kg

∴ Total selling price = [16 × (25 + x)] = 400 + 16x

Now, as given in question trader makes a profit of 15%, and we all know that

Cost price = Selling price – Profit

∴ 370 + 12.85x = 400 + 16x – 15% (400 + 16x)

⇒ 15% (400 + 16x) = 30 + 3.15x

⇒ 400 + 16x = 100 × (30 + 3.15x) / 15

⇒ 400 + 16x = 200 + 21x

⇒ 200 = 5x

⇒ x = 40kgs