Solve each problem. See Example 7.
67.The weight y(in pounds) of a man taller than 60 in. can be approximated
by the linear equation
where xis the height of the man in inches.
(a)Use the equation to approximate the weights of men whose heights
are 62 in., 66 in., and 72 in.
(b)Write the information from part (a) as three ordered pairs.
(c)Graph the equation, using the data from part (b).
(d)Use the graph to estimate the height of a man who weighs 155 lb. Then
use the equation to find the height of this man to the nearest inch.
68.The height y(in centimeters) of a woman is related to the
length of her radius bone x(from the wrist to the elbow) and is
approximated by the linear equation
(a)Use the equation to approximate the heights of women with
radius bone of lengths 20 cm, 26 cm, and 22 cm.
(b)Write the information from part (a) as three ordered pairs.
(c)Graph the equation, using the data from part (b).
(d)Use the graph to estimate the length of the radius bone in a woman who is 167 cm
tall. Then use the equation to find the length of the radius bone to the nearest
centimeter.
69.As a fundraiser, a club is selling posters. The printer charges a $25 set-up fee, plus $0.75
for each poster. The cost yin dollars to print xposters is given by
(a)What is the cost yin dollars to print 50 posters? To print 100 posters?
(b)Find the number of posters xif the printer billed the club for costs of $175.
(c)Write the information from parts (a) and (b) as three ordered pairs.
(d)Use the data from part (c) to graph the equation.
70.A gas station is selling gasoline for $3.50 per gallon and charges $7 for a car wash. The
cost yin dollars for xgallons of gasoline and a car wash is given by
(a)What is the cost yin dollars for 9 gallons of gasoline and a car wash? For 4 gallons
of gasoline and a car wash?
(b)Find the number of gallons of gasoline xif the cost for gasoline and a car wash is $35.
(c)Write the information from parts (a) and (b) as three ordered pairs.
(d)Use the data from part (c) to graph the equation.
71.The graph shows the value of a sport-utility
vehicle (SUV) over the first 5 yr of ownership.
Use the graph to do the following.
(a)Determine the initial value of the SUV.
(b)Find the depreciation(loss in value) from
the original value after the first 3 yr.
(c)What is the annual or yearly depreciation in
each of the first 5 yr?
(d)What does the ordered pair 1 5, 5000 2 mean in the context of this problem?
y=3.50x+7.
y=0.75x+25.
y=3.9x+73.5.
y=5.5x-220,
3.5 Graphing Linear Inequalities in Two Variables
y
x
0 12345
15,000
30,000
Year
SUV VALUE
Value (in dollars)
x
x
