Quandaries
and Queries
My question is how do you prepare a 100ml of a 30% alcohol solution using 95% alcohol?
Justin (Student)
Grade 10
Hi Justin,
You want to end up with 100ml of liquid, 30% of which
is alcohol. 30% of 100ml is 30/100
100
= 30 ml. Thus you need 30 ml of alcohol and 70 ml of water.
The question now is, how much of the 95% solution do you need to give you 30 ml of alcohol? To ask this question using algebra, let x ml be the amount of the 95% solution that you need, then the question becomes
What is x if 95% of x is 30 ml?
Said as an equation, solve for x if
95/100
Can you complete the problem now?
Penny