Multiple choice

A cask contains a mixture of $49\ litres$ of wine and water in the ratio $5 : 2$. How much water must be added to it so that the ratio of wine to water is $7 : 4$?

  1. $3.5\ litres$
  2. $7\ litres$
  3. $4\ litres$
  4. $6\ litres$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Initial wine = 35L, water = 14L. Let x be water added. (35 / (14+x)) = 7/4. 140 = 98 + 7x. 7x = 42, so x = 6.