Algebra 1 Common Core Student Edition, Grade 8-9

@ 17. Writing Give two d ata sets th a t are correlated b u t do not have a causal relationship.

18. Business D uring one m o n th at a local deli, th e a m o u n t of h a m sold decreased
    as th e a m o u n t of turkey sold increased. Is this an exam ple of positive correlation,
    negative correlation, or no correlation?
    @ 19. Think About a Plan S tudents m easu red th e diam eters a n d circum ferences of the
    tops of a variety of cylinders. Below are th e d ata th a t they collected. Estim ate th e
    d iam eter of a cylinder w ith circum ference 22 cm.
    F '..................
    Cylinder Tops

■■

Diameter (cm) 3 3 5 6 8 00 S°Ln 10 10 12

Circumference (cm) 9.3 9.5 16

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25.6 29.5 31.5 30.9

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39.5

• How can you use a scatter plot to find an eq u a tio n of a tren d line?


• How can you use th e equ atio n of th e tren d line to m ake an estim ate?
  2 0. U.S. P o p u la tio n Use th e d ata below.
  y ............ i
  Estimated Population of the United States (thousands)
  Year 2000 2001 2002 2003 2004 2005 2006
  Male 138,482 140,079 141,592 142,937 144,467 [ 1 4 5 , 9 7 3 1 4 7 , 5 1 2
  Female 143,734 145,147 146,533 147,858 149,170 150,533 151,886

Source: U.S. Census Bureau

a. Make a scatter plot of th e d ata pairs (m ale population, fem ale population).

b. Draw a tre n d line an d w rite its equation.

c. Use your equation to p redict the U.S. female p o p u latio n if th e U.S. m ale

po pulation increases to 150,000,000.

d. Reasoning C onsider a scatter plot of th e data pairs (year, m ale p opulation).

W ould it be reasonable to use this scatter plot to predict th e U.S. m ale p o pulation

in 2035? Explain your reasoning.

21. a. Graphing Calculator Use a graphing calculator to find th e equ atio n of the line
    of best fit for th e data below. Let x = 8 re p resen t 1998, x = 9 rep resen t 1999,
    and so on.

U.S. C om puter and Video G am e U nit Sales

Year (^1998199920002001200220032004 200520062007)
Unit Sales
(m illions) 152.4 184.5 196.3 210.3 225.8 240.9 249.5 '229.5 241.6.267.9
Source: The NPD Group/Retail Tracking Service
b. W hat is the slope of th e line of best fit? W hat does th e slope m ean in term s of the
n u m b e r of com puter a n d video gam e units sold?
c. W hat is th e y-intercept of the line of b est fit? W hat does th e y -intercept m ean in
term s of the n u m b e r of co m p u ter an d video gam e units sold?
342 Chapter 5 Linear Funct ions