Question

A business discovers a linear relationship between the number of shirts it can sell and the price per shirt. If the shirts cost $25 then 8,000 will be sold. But if the shirts cost $40, only 5,000 will be sold. Find a linear function that models this and predict the number of shirts that will be sold if the cost is $20.
show work.

Answer 1

It makes sense to let the # of shirts sold be the variable dependent upon the unit cost per shirt.

Notice that the # sold declines as the price increases.

Thus, the slope of this line will be -.
      
         8000 - 5000       3000 shirts
m = ------------------- = ----------------- = -200 shirts per dollar price increase 
             25 - 40                 -15