Question

calculate the amount of 90% and 50% alcohol should be mixed to get 75% alcohol ?

Answer 1

Explanation:

For the sake of simple maths, let’s say you have 50ml of 70% alcohol solution, and 50ml of 50% alcohol solution.

70% of 50 is 35, so in the first solution you have 35ml of alcohol.

50% of 50 is obviously 25. So in the second solution you have 25ml of alcohol.

Combing the two would therefore give you 60ml of alcohol in 100ml of solution- so you’ve made a 60% solution.