Multiple choice

Sulphuric acid and water in 2 jars A and B are in the ratio 1 : 5 and 5 : 4 respectively. In what ratio should the content of the two jars be mixed to obtain a mixture of acid and water in the ratio 2 : 7?

  1. 2 : 3

  2. 6 : 1

  3. 3 : 4

  4. 4 : 5
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Using alligation on acid content: Jar A = 1/6, Jar B = 5/9, Mixture = 2/9. (5/9 - 2/9) : (2/9 - 1/6) = (3/9) : (4/18 - 3/18) = (1/3) : (1/18) = 6 : 1.

AI explanation

Using the rule of alligation, the acid part in jar A is 1/6, in the target mixture is 2/9, and in jar B is 5/9. The ratio of the quantity taken from jar A to jar B is the difference between the target and jar B (5/9 - 2/9 = 3/9) to the difference between jar A and the target (2/9 - 1/6 = 1/18). Simplifying the ratio 3/9 to 1/18 gives 6 to 1.

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