Word Problem

[AnarktTearia]

How anyone help me solve this?

 

A druggist haspure alcohol and a 20% solution. How many gallons of each should be used in forming 4 gallons of a 30% solution?

[yammers]

Hi AnarktTearia, I'm not a math guy, but since no-one else has anwsered your problem I'll take a jab at it.

 

30% of 4 gallons is 1.2 gallons of alcohol, and 2.8 gallons of the (other). Since you'll be using 100% alcohol to increase the solution to 30% from 20%, you know that the 2.8 gallons of (other) is all that will be used; since the initial solution is 20% alc, then the 2.8 is 80%; the solution is 2.8/ 80% = 3.5 gallons of 20%. The rest (.50 gal) would be alcohol.