3.21 8th Grade: Evaluate Functions

1. Denise decides to study abroad in France. She has to exchange her dollars for Euros. The following function describes the exchange rate between dollars and Euros:

ƒ(d) = .75d.

Find ƒ(200)


2. The profit from selling s number of t-shirts is described by the following function:

p(s) = 8s – 500.

Find p(70).


3. The value of a car is given by the following function:

v(t) = 20,000(.90)^t.

Find v(1)


4. Daniel’s income for the fall semester is described by the following function:

ƒ(h) = 1,000 + 9h.

Find ƒ(320)


5. Felix’s total credit card balance is described by the following function:

c(p) = p(1.30).

What is p(2500)?


6. The study time per credit hour is described by the following function.

s(c) = 3c

What is s(15)?



7. The total amount of gas money is determined by the following function:

c(g) = 600g/30.

What is c($3.00)?


8. The number of students enrolled in the 9 am Calculus class is described by the following function:

ƒ(p) = 16p.

Find ƒ(20).


9. The number of Facebook friends you make d days after arriving on campus is described by the following function:

ƒ(d) = 2^d.

Find ƒ(7).


10.  A mechanic charges $125 plus $25 per hour of labor. The equation c=25n+125 describes the total she would charge for a service visit, where n represents the number of hours of labor and c is the total cost. Graph the equation and using the graph, find how much he charges when she works 3 hours.



 11.  An airplane whose capacity is 100 passengers is to be chartered for a flight to Europe. The fare is to be $150 per person, if 60 people buy tickets. However, the airline agrees to reduce the fare for ever passenger by $1 for each additional ticket sold. How many tickets should be sold to maximize the ticket revenue for this flight?


12.  No more than 65 freshman and sophomores may participate in the math club. There are three times as many freshman as sophmores. Let x represent the number of freshman. Let y represent the number of sophmores. Write and graph an inequality that describes the different number of freshman and sophmores in the math club.



13.  Suppose you are at the gas station filling your tank with gas. The function C(g) represents the cost C of filling up the gas tank with g gallons. Given the equation:
C(g)=3.03(g)
a) What does the number 3.03 represent?
b) Find C(2)
c) Find C(9)
d) For the average motorist, name one value for g that would be inappropriate for this function�s purpose. Explain why you chose the number you did.
e) If you were to graph C(g), what would be an appropriate domain? Range? Explain your reasoning.