Solve the problem.
-A merchant has coffee worth $20 a pound that she wishes to mix with 30 pounds of coffee worth $90 a pound to get a mixture that can be sold for $50 a pound. How many pounds of the $20 coffee should be used?
A)40 lb
B)70 lb
C)35 lb
D)20 lb

Question

Quizplus · Accepted Answer

The problem can be solved using the concept of weighted averages or the mixture rule. Let x be the amount of $20 coffee. The total value of the $20 coffee is 20x dollars, and the total value of the $90 coffee is 30*90 = 2700 dollars. The mixture's total value is (x + 30) pounds at $50 per pound, which equals 50(x + 30) dollars. Setting the total values equal gives the equation: 20x + 2700 = 50(x + 30). Solving for x gives x = 40 pounds.

Solve the Problem. -A Merchant Has Coffee Worth $20 a Pound That She