# multi-step problem

• Jun 4th 2008, 06:31 PM
heather_meaghan
multi-step problem
problem: Seminole Dairy Farm has 100 gal of milk that is 4.6% butterfat. How much skim milk (no butterfat) should be mixed with it to make milk that is 3.2% fat?

a: make a table.
b: let x be the amount of skim milk. Complete the columns that show the amount and the percent of butterfat.
c: to find the amount of butterfat in a solution, what two quantities must be multiplied?
d: write expressions that show the amount of butterfat in each solution.
e: Write and solve an equation to answer the problem.

• Jun 5th 2008, 04:25 AM
sean.1986
Well if you wanted to half the percentage of butterfat then you'd add 100 gallons of skimmed milk, i.e. the amounts would be a 1:1 ratio.

The ratio gives the percentage that you want to keep and the percentage you want to remove.

As you want to keep 16 23rds of the butterfat (3.2/4.6), you have a 16:7 ratio of the amounts that need to be used.

So if 100 gallons is 16/23, then 7/23 is...

(7/23) / (16/23) * 100 = 7/23 * 23/16 * 100 = 7/23 * 2300/16 = 16100/368 = 43.75 gallons of skimmed milk should be added