Question

1. A set of weights includes a 5 lb barbell and 8 pairs of weight plates. Each pair, p,

weights 10 lbs. If x pair of weight plates are added to the barbell, the total weight of the
barbell in pounds can be represented by the function
f(x) = 10x + 5. What is a reasonable range of the function in this situation?

Answer 1

5 <= y <= 85

Explanation:

Since the lowest weight possible is 5lbs (just the barbell and no weights) the lowest point of the range is 5lbs (the y intercept when x = 0)

The highest weight possible is 85lbs since, there is only 8 pairs of weight plates (8 is the input value) and the pairs each weigh 10lbs (the slope of the graph) + 5lbs from the barbell (y-intercept).

Using the function given, if you input 8 as the x value, you get

85 = 10(8) + 5

So the highest value of the range is 85lbs, therefore the range is 5 <= y <= 85.