Multiple choice

A milk vendor has 2 cans of milk. The first contains 25% water and the rest milk. The second can contains 50% water. How much of the mixture should he mix from each of the containers, so as to get 12 litres of solution such that the ratio of water to pure milk is 3 : 5?

  1. 4 litres, 8 litres

  2. 6 litres, 6 litres

  3. 5 litres, 7 litres

  4. 7 litres, 5 litres
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Can 1: 25% water (1/4). Can 2: 50% water (1/2). Target: 12L with 3:5 water to milk ratio, which is 3/8 water (37.5%). Using alligation: (1/2 - 3/8) : (3/8 - 1/4) = (1/8) : (1/8) = 1:1. Total 12L means 6L from each.

AI explanation

Using the rule of alligation on the water percentages, the ratio of the volume needed from the first can to the second can is (50% minus 37.5%) to (37.5% minus 25%). This simplifies to a ratio of 2 to 1 for the respective volumes needed from the first and second cans. Since the total required mixture is 12 litres, the vendor must take 6 litres from the first can and 6 litres from the second can to maintain the 2 to 1 ratio.

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