You need a 15% alcohol solution. On hand, you have a 240 ml of a 10% alcohol mixture. You also have 35% alcohol mixture. How much of the 35% mixture will you need to add to obtain the desired solution

Answer 1

There are a few ways to approach this problem.

Method I (algebra):

(240 ml)(10%) + (x ml)(35%) = (240 ml + x ml)(15%)

2400 + 35x = 3600 + 15x

20x = 1200

x = 60 mls of the 35% alcohol should be added to the 240 ml of 10% alcohol to obtain 300 ml of 15% alcohol

Method II (alligation)

10%..................20 parts

............15%.........

35%..................5 parts

Since 20 parts = 240 mls, the 5 parts would be 60 mls of the 35% is needed