n what ratio should a variety of rice costing Rs. 6 per kg be mixed with another variety of rice costing Rs. 8.75 per kg to obtain a mixture costing Rs. 7.50 per kg?
Correct answer: A. 5 : 6
- A. 5 : 6
- B. 3 : 4
- C. 7 : 8
- D. 8 : 9
Explanation
Using alligation, the quantities of rice at Rs. 6 per kg and Rs. 8.75 per kg are in the ratio (8.75 - 7.50):(7.50 - 6) = 1.25:1.50 = 5:6. The weighted average is therefore Rs. 7.50 per kg. The likely mistake is reversing the ratio to 6:5, which would make the mixture cost more than Rs. 7.50 per kg.
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