Quote:
A 5-liter flask contains 3.5 liters of a solution that’s 5% alcohol. If 1 liter of solution spills out of the flack, and the flask is then filled to capacity with pure alcohol. What percent of the resulting solution is alcohol?
Alcohol in 3.5 litres of a solution = 5% of 3.5 = 0.175 litres
Alcohol in 1 litre of solution that spills out of the flack = 5% of 1 = 0.05 litres
Alcohol in 2.5 litres (3.5-1) of a solution left in flask= 0.175 - 0.05 = 0.125 litres
Amount of pure alcohol added to flask = 2.5
Total amount of alcohol in 5 litres of a solution = 2.5 + 0.125 = 2.625 litres
percent of the alcohol in resulting solution = 2.625 / 5 *100% = 52.5%
IMO E