Question

15 litres of mixture contains 20% alcohol and rest water, 3 litres of water be mixed with it, the percentage of alcohol in the new mixture would be.

Answer 1

Case 1 :
Total amount of mixture = 15 L
Alcohol : 20 % of 15 L
 = 20 / 100 * 15
 = 3 L
Water : 15 L - 3 L = 12 L

Case 2
Total amount of mixture = 15 L + 3 L = 18 L
Alcohol : 
Percentage = 3 / 18 * 100
                   = 16. 67 %

Answer 2

Answer:

Percentage of alcohol is 16.67%.

Step-by-step explanation:

Total amount of mixture = 15 liters

But mixture contains 20% alcohol

Amount of alcohol = 20 % of 15 L

                               = 15 × (20 / 100)

                               = 15/5

                               = 3 liters

Amount of Water = 15 - 3 = 12 liters

Now if we add 3 liters of water in mixture

Total amount of mixture = 15 + 3 = 18 liters

Amount of alcohol = 3 liters

∴ Percentage of alcohol = (3 / 18) × 100

                                        = 100/6

                                        = 16. 67 %