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CPM eBooks ­ CC Algebra
7­73. The U.S. Census Bureau takes a census every 10 years. The population in 2000 was estimated at
281.4 million people. A model created at the time predicted that the population grew at about 2% per
year. Homework Help ✎
a. How many people would the Census Bureau have expected to count in the 2005 census?
b. If the Census Bureau had conducted a count in 2010, how many people would it have expected to
count?
c. The actual 2010 census put the population at 309 million people. What is the residual? What does
it mean? 7­74. Find values of a and b that make each system of equations true (i.e., solve each system). Be sure to
show your work or explain your thinking clearly. Homework Help ✎
a. 6 = a ∙ b0 2
24 = a ∙ b
b. 32 = a ∙ b2
3
128 = a ∙ b
7­75. Jack and Jill were working on simplifying the expression at right, but they were
having some trouble. Then Jill had an idea.
“Can’t we separate the parts?” she said. “That way, it might be easier to
tell what we can simplify.” She rewrote the expression as shown at right.
“Okay,”said Jack. “Now we can rewrite each of the parts with negative exponents and simplify.”
Homework Help ✎
a. Help Jack and Jill finish simplifying their expression. b. Use their idea to rewrite and simplify .
7­76. A particular sequence can be represented by t(n) = 2(3)n. Homework Help ✎
a. What are t(0), t(1), t(2), and t(3)?
b. Graph this sequence. What is the domain?
c. On the same set of axes, graph the functionf(x) = 2(3)x .
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CPM eBooks ­ CC Algebra
d. How are the two graphs similar? How are they different?
7­77. Solve the system of equations at right algebraically. Homework Help ✎
7­78. Each teams in Ms. Zaleski’s class cut a circular disks from cardboard file folders. They could cut
the disks any size they chose. The weight and radius were recorded. The information is shown in the
table below. Since students chose the radius, consider radius the independent variable. Homework Help
✎
a. Make a scatterplot for the data and sketch it onto your paper. Describe the association between
weight and radius. b. The weight of the cardboard disk depends on its area. What kind of equation do you suggest to
model this data? c. Model the data with a regression equation. Does the y­intercept of your model make sense in this
context?
d. What do you predict a 7­cm disk will weigh? Use appropriate precision in your answer. http://textbooks.cpm.org/bookdb.php?title=cca&name=7.1.6&type=lesson#7­73
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