Difficulty: Easy
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:
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
Discussion & Comments