For each situation, (a)write an equation in the form ,(b)find and interpret the
ordered pair associated with the equation for ,and (c)answer the question. See
Examples 7(b) and 7(c).
81.A ticket for the 2010 Troubadour Reunion, featuring James Taylor and Carole King,
costs $112.50. A parking pass costs $12. (Source:Ticketmaster.) Let xrepresent the
number of tickets and yrepresent the cost. How much does it cost for 2 tickets and a
parking pass?
82.Resident tuition at Broward College is $87.95 per credit hour. There is also a $20 health
science application fee. (Source:www.broward.edu) Let xrepresent the number of credit
hours and yrepresent the cost. How much does it cost for a student in health science to
take 15 credit hours?
83.A membership in the Midwest Athletic Club costs $99, plus $41 per month. (Source:
Midwest Athletic Club.) Let xrepresent the number of months and yrepresent the cost.
How much does the first year’s membership cost?
84.For a family membership, the athletic club in Exercise 83charges a membership fee of
$159, plus $60 for each additional family member after the first. Let xrepresent the num-
ber of additional family members and yrepresent the cost. What is the membership fee
for a four-person family?
85.A cell phone plan includes 900 anytime minutes for $60
per month, plus a one-time activation fee of $36. A
Nokia 6650 cell phone is included at no additional
charge. (Source:AT&T.) Let xrepresent the number of
months of service and yrepresent the cost. If you sign a
1-yr contract, how much will this cell phone plan cost?
(Assume that you never use more than the allotted num-
ber of minutes.)
86.Another cell phone plan includes 450 anytime minutes
for $40 per month, plus $50 for a Nokia 2320 cell phone
and $36 for a one-time activation fee. (Source:AT&T.)
Let xrepresent the number of months of service and y
represent the cost. If you sign a 1-yr contract, how much
will this cell phone plan cost? (Assume that you never
use more than the allotted number of minutes.)
87.There is a $30 fee to rent a chain saw, plus $6 per day. Let xrepresent the number of days
the saw is rented and yrepresent the charge to the user in dollars. If the total charge is
$138, for how many days is the saw rented?
88.A rental car costs $50 plus $0.20 per mile. Let xrepresent the number of miles driven and
yrepresent the total charge to the renter. How many miles was the car driven if the renter
paid $84.60?
Solve each problem. In part (a), give equations in slope-intercept form. ( Round the slope to
the nearest tenth.) See Examples 8 and 9.
89.Total sales of digital cameras in the United States (in
millions of dollars) are shown in the graph, where the
year 2003 corresponds to.
(a)Use the ordered pairs from the graph to write an
equation that models the data. What does the slope
tell us in the context of this problem?
(b)Use the equation from part (a) to approximate the
sales of digital cameras in the United States in 2007.
x= 0
x= 5
y=mx+b
172 CHAPTER 3 Graphs, Linear Equations, and Functions
0231
2000
4000
6000
8000
x
y
(0, 3921)
(3, 7805)
Year
Sales
(in millions of dollars)
Source: Consumer Electronics
Association.
Digital Camera Sales
