High School

A man buys 2 varieties of rice, the first at Rs. 65 per kilo and the second at Rs. 72 per kilo. After thoroughly mixing them, he sells the mixture for Rs. 84 per kilo, making a 20% profit. If he sold 21 kilos of this mixture, how many kilos of the first variety of rice must he have bought?

Answer :

Answer:

6

Step-by-step explanation:

You want the number of kilos of rice at ₹65 per kg that are mixed with rice at ₹72 per kg such that sale of 21 kg of the mixture at ₹84 results in a 20% profit.

Setup

Let x represent the number of kg of ₹65 rice. Then (21-x) is the number of kg of ₹72 rice. The purchase price is multiplied by 1.20 to find the selling price. The total revenue from sales is ...

(65x +72(21-x))×1.20 = 84×21

Solution

Simplifying the equation gives ...

1.20×72×21 -1.20×7x = 84×21 . . . . . . . eliminate parentheses

1814.40 -8.4x = 1764 . . . . . . . . . . . simplify the products

50.4 = 8.4x . . . . . . . . . . . . . . . . subtract 1764-8.4x

6 = x . . . . . . . . . . . . . . . . . . divide by 8.4

6 kilos of ₹65/kg rice were bought for the mix.

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