Chapter 4 Section 4

Applications involving Systems of Equations in two Variables

Activity 7

• These all need to be written up using the format described in the last slide

A problem from Wonderland

In Lewis Carroll’s Through the Looking Glass, Tweedledum says to Tweedledee, “The sum of your weight and twice mine is 361 pounds.” Then Tweedledee says to Tweedledum, “Contrariwise, the sum of your weight and twice mine is 362 pounds.” Find the weight of each.

• Green Diamond can either convert logs into lumber or plywood. In a given day the mill turns out 42 units of plywood and lumber combined. It makes a profit of $2500 on each unit of lumber and $4000 on each unit of plywood. How many units of each type were produced if they sold all 42 units and made a profit of $124,500?

• Staples recently sold a graph-paper notebook for $2.50 and a college-ruled notebook for $2.30. At the start of the semester 50 of these notebooks were sold for a total of $118.60. How many of each type of notebook were sold?

• The Nutty Professor sells cashews for $6.75 per pound and Brazil nuts for $5.00 per pound. How much of each type should be used to make a 50-pound mixture that sells for $5.70 per pound?

• Soybean meal is 16% protein and corn meal is 9% protein. How many pounds of each should be mixed to get a 350-pound mixture that is 12% protein?

• An executive nearing retirement made two investments totaling $15,000. In one year, these investments yielded $1432 in simple interest. Part of the money was invested at 9% and the rest at 10%. How much was invested at each rate?