a The amount of sales and the number of sold muffins vary directly.
B
b The phrase at least is the same thing as saying greater than or equal to.
A
a s= 2.5m
B
b At least 100 muffins
Practice makes perfect
a The function that describes the amount of sales given the number of sold muffins will be a direct variation function. This is because the recorded sales only depends on the number of sold muffins. Therefore to get s we have to multiply m with some coefficient k.
Direct Variation
s = km
[-1em]
Constant of Variation: kTo find k, we need to choose one ordered pair from the table of values and solve for k. We can, for example, choose the fourth value (20,50).
b We can use the function we created from Part A to find the minimum number of muffins that must be sold. Recall that the phrase at least is the same thing as saying greater than or equal to. Since s represents sales, we want s to be greater than or equal to 250.
s ≥ 250
By substituting s=2.5m, we can then solve for m by performing inverse operations.
