In what ratio must wheat at Rs. 1.60 per kg be mixed with wheat at Rs. 1.45 per kg so that the mixture is worth Rs. 1.54 per kg (no wastage)?
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A2 : 3
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B3 : 2
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C3 : 4
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D4 : 3
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E5 : 3
Answer
Correct Answer: 3 : 2
Explanation
Introduction / Context:Alligation is the quickest way to find the mixing ratio for a target mean price between two known prices. The quantities are inversely proportional to the differences from the mean.
Given Data / Assumptions:
- Dearer wheat: Rs. 1.60/kg.
- Cheaper wheat: Rs. 1.45/kg.
- Mixture price: Rs. 1.54/kg.
Concept / Approach:For prices P1 (dearer) and P2 (cheaper) yielding mean M, the required ratio P1 : P2 = (M − P2) : (P1 − M).
Step-by-Step Solution:Differences: M − P2 = 1.54 − 1.45 = 0.09P1 − M = 1.60 − 1.54 = 0.06Hence 1.60 : 1.45 quantities = 0.09 : 0.06 = 3 : 2
Verification / Alternative check:Weighted average with 3 kg of 1.60 and 2 kg of 1.45: price = (3*1.60 + 2*1.45)/5 = (4.80 + 2.90)/5 = 7.70/5 = 1.54.
Why Other Options Are Wrong:2 : 3 or 4 : 3 give means other than 1.54; only 3 : 2 balances the differences correctly.
Common Pitfalls:Using direct differences instead of inverse differences, which reverses the intended ratio.
Final Answer:3 : 2