A beaker is filled with a liquid, 3 parts of which are water and 7 parts of some medicine. What part of the mixture should be replaced with water so that the resultant mixture has water and medicine in a ratio1 : 1?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is Option 1 i.e. 2/7.
Given:
Parts of water in the liquid = 3
Parts of medicine in the liquid = 7
Explanation:
Let the beaker contains 10 liters of liquid.
Amount of Water = 3 litres
Amount of Medicine = 7 litres
Let x liters of this liquid be replaced with water.
Water = 3x/10 and Medicine = 7x/10
Water before replacement + 7x/10 = Medicine before replacement - 7x/10
Medicine before replacement - Water before replacement = 7x/10 + 7x/10 = 7x/5
⇒ 7/10 - 3/10 = 7x/5
⇒ 4/10 = 7x/5
⇒ x = 20/70
⇒ x = 2/7