Question

A distrubutor wants to make 1,000 pounds of trail mix that is 8% raisins. He will use a mix that is 5% raisins and a mix that is 20% raisins. How many pounds of each should he use?

Answer 1

5% raisin mix: 800 lbs

20% raisin mix: 200 lbs

Explanation:

Let number of 5% be x; and number of 20% be a.

x + y = 1000

5% · x + 20% · y = 8% of 1000 pounds

0.05x + 0.2y = 80

x = 1000 - y

0.05(1000 - y) + 0.2y = 80

50 - 0.05y + 0.2y = 80

0.15y = 30

y = 200

x = 1000 - y

x = 1000 - 200

x = 800

Answer 2

He should use 800 pounds of trail mix 5% raisins and 200 pounds of trail mix 20% raisins

Explanation:

System of Equations

Let's call

x = pounds of trail mix 5% raisins

y = pounds of trail mix 20% raisins

The distributor wants to make 1,000 pounds of trail mix, thus:

x + y = 1,000 [1]

The mix must be 8% raisings as a combination of x and y, thus:

5x + 20y = 8*1,000 = 8,000

Dividing by 5:

x + 4y = 1,600 [2]

Subtracting [2] and [1]:

4y - y = 1,600 - 1,000

Operating:

3y = 600

y = 200

From [1]

x = 1,000 - y = 1,000 - 200

x = 800

He should use 800 pounds of trail mix 5% raisins and 200 pounds of trail mix 20% raisins