At the deli counter at the supermarket, Nigel paid $10 for 2 1/2 pounds of roast beef. The cost of deli meat is proportional to his weight. What is the equation for the graph of the proportional relationship?
Let x be the weight of roast beef in pounds and y be the cost in dollars.
Since the cost of deli meat is proportional to the weight, we have y = kx, where k is the constant of proportionality.
Given that Nigel paid $10 for 2 1/2 pounds of roast beef, we can set up the following equation:
10 = k(2.5)
Divide both sides of the equation by 2.5 to isolate k:
10/2.5 = k(2.5)/2.5
4 = k
So the equation for the graph of the proportional relationship is y = 4x.