Science:Math Exam Resources/Courses/MATH104/December 2015/Question 08 (a)/Solution 1

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The two key pieces of information required for this question are:

  • "when the unit price is per toaster, then the weekly demand is toasters"
  • "for every decrease in the unit price, the weekly demand increases by toasters"

from which it is clear that the unit price and the weekly demand are linearly related.


Using the 'slope-point' form of the equation of a line and considering as a function of , we can write

where is a 'coordinate' consisting of a price and the demand at that price, and is the slope of the line in the -plane.

Hence we can take and (when decreases by 2, increases by 10). Thus

Note: Considering as a function of is equally correct and leads to the equivalent answer