Question

For a special event, a restaurant charges a one-time setup fee, plus a charge for each person attending the event. The charge for 5 people is $100. The charge for 10 people is $162.50.
Part 1) Write a linear function that models the cost, y, of the total event cost based on the number of people, x, attending the event.

Part 2) Describe what the rate of change and initial value mean in this situation.

Answer 1

Any linear function is of the form y=mx+b

Here m is slope and b is y intercept.

Slope is difference in y divided by different in x values .

In the question for 5 persons cost is $100 and for 10 persons cost is $162.50

So the points are (5,100) and (10,162.50)

Slope m=$\frac{162.50-100}{10-5}$=12.50

We can find the value of b by taking m=12.50 and (x,y)=(5,100)

Substitute these values in y=mx+b

100=12.50(5)+b

100=62.50+b

Subtracting 62.50 both sides

b=100-62.50

b=37.5

a) Put m=12.50 and b=37.50 to get the equation

y=12.50x+37.50

b)Rate of change is the m value or the slope of the function.

Initial value that is (5,100) gives us one of the points to find the rate of change.