Mixture Problems (Jump to: Lecture | Video )

Imagine that red marbles sell for $2.00 a pound, and blue marbles sell for $1.00 a pound. You have 10 pounds of red marbles. How many pounds of blue marbles should be mixed in to create a mixture worth $1.40 a pound?

Figure 1.

Using the totals, we can arrange the equation to solve for "x":

20 + x = 1.40(10 + x)

20 + x = 14 + 1.4x

6 = 0.4x

15 = x

It would take 15 pounds of blue marbles to create a mixture worth $1.40 a pound.