Question

A certain drug is made from only two ingredients: compound A and compound B. There are 3 milliliters of compound A used for every 5 milliliters of compound B. If a chemist wants to make 408 milliliters of the drug, how many milliliters of compound A are needed?

Answer 1

153

Explanation:

The formula is 3 mL of A to 5 mL of B.

Let's say the chemist uses just the numbers in the formula.

Add 3 mL of A to 5 mL of B.

3 mL + 5 mL = 8 mL

The chemist ends up with 8 mL of the drug.

He really want 408 mL.

408 mL is how many times greater than 8 mL?

408/8 = 51

He needs to use 51 times the numbers in the formula.

51 * 3 mL of A + 51 * 5 mL of B =

= 153 mL of A + 255 mL of B

= 408 mL of the drug

Answer: 153