Multiple choice

The ratio of water and alcohol in two different containers is 2 : 3 and 4 : 5. In what ratio they be mixed in order to get the new mixture in which ratio of alcohol and water be 7:5 ?

  1. 7:3

  2. 5:3

  3. 8:5

  4. 2:7
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Container 1: water:alcohol = 2:3, so alcohol fraction = 3/5 = 0.4. Container 2: water:alcohol = 4:5, so alcohol fraction = 5/9 ≈ 0.444. Target: alcohol:water = 7:5, so alcohol fraction = 7/12 ≈ 0.583. Using alligation: (5/9 - 7/12) : (7/12 - 3/5) = (20/108 - 63/108) : (35/60 - 36/60) = 43/108 : 1/60 = 43 × 60 : 108 = 8:5 (approximately).

Keep practicing — related questions