Beginning Algebra, 11th Edition

(a)Write five ordered pairs from the data.

(b)Plot the ordered pairs. Do the points lie approximately in a straight line?

(c)Use the ordered pairs and to write an equation of a line that

approximates the data. Give the final equation in slope-intercept form.

(d)Use the equation from part (c) to estimate the average annual cost at 2-year colleges

in 2009 to the nearest dollar. (Hint:What is the value of xfor 2009?)

82.The table gives heavy-metal nuclear waste (in thousands of metric tons) from spent reactor
fuel stored temporarily at reactor sites, awaiting permanent storage. (Source:“Burial of
Radioactive Nuclear Waste Under the Seabed,” Scientific American,January 1998.)

1 1, 20792 1 4, 23612

SECTION 3.4 Writing and Graphing Equations of Lines 221

Let represent 1995, represent 2000 (since ), and so on.

(a)For 1995, the ordered pair is Write ordered pairs for the data for the other

years given in the table.

(b)Plot the ordered pairs Do the points lie approximately in a straight line?

(c)Use the ordered pairs and to write the equation of a line that

approximates the other ordered pairs. Give the equation in slope-intercept form.

(d)Use the equation from part (c) to estimate the amount of nuclear waste in 2015. (Hint:

What is the value of xfor 2015?)

The points on the graph show the number of colleges that teamed up with banks to issue stu-
dent ID cards which doubled as debit cards from 2002 through 2007. The graph of a linear
equation that models the data is also shown.

1 0, 32 2 1 25, 76 2

1 x, y 2.

1 0, 32 2.

x= 0 x= 5 2000 - 1995 = 5

83.Use the ordered pairs shown on the graph to write an equation of the line that models the
data. Give the equation in slope-intercept form.

84.Use the equation from Exercise 83to estimate the number of colleges that teamed up
with banks to offer debit IDs in 2004, the year with unavailable data.

*Estimated by the U.S.

Department of Energy.

Year x Waste y

1995 32

2000 42

2010* 61

2020* 76

0

25

50

75

100

125

150

Number of Colleges

Year

'02 '03 '04* '05 '06 '07

(2007, 127)

(2002, 52)

Source: CR80News.

* Data for 2004 unavailable.

Debit IDs

(^12) /1 (^012) /14
FVALIROMD DEBIT
BANKSAVINGS
STUDENT ID
Julia Marcus
Undergraduate 2010
ID# 3971100085240
y
x