How many kgs of wheat costing Rs. 8 per kg must be mixed with 86 kg of rice…

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How many kgs of wheat costing Rs. 8 per kg must be mixed with 86 kg of rice costing Rs. 5 per kg so that 20% gain may be obtained by selling the mixture at Rs. 7.20 per kg?

  1. A.

    25 kg

  2. B.

    72 kg

  3. C.

    36 kg

  4. D.

    43 kg

Attempted by 11 students.

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Correct answer: D

Answer: 43 kg

Find the cost price (CP) of the mixture. Selling price = Rs. 7.20 and desired profit = 20%, so

CP of mixture = 7.20 × 100 / 120 = Rs. 6 per kg.

Using the prices: wheat = Rs. 8/kg (dearer) and rice = Rs. 5/kg (cheaper), apply allegation:

  • Ratio of wheat to rice = (mean − price of rice) : (price of wheat − mean) = (6 − 5) : (8 − 6) = 1 : 2.

This means for every 1 part of wheat there are 2 parts of rice. Given rice = 86 kg (the 2 parts), the quantity of wheat (1 part) = 86 ÷ 2 = 43 kg.

Therefore, 43 kg of wheat must be mixed with 86 kg of rice.

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