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Sample Answers
1. a) There is a downward trend that shows cars are worth less
as they get older.
b) No; there are 1-year-old cars with prices of $17 000,
$18 000, and $19 500.
c) Make and model, mileage, rust, condition
2. a) There is an upward trend; in general, older students read
faster than younger students.
b) About 110 months
c) I think the reading speed of a person aged 500 months
would be about 300 words per minute. Reading speed
tends to increase with age, but I think people would reach
a point where their reading speed would not increase
anymore.
3. a)
Made
Field Goals
12
10
8
6
4
2
0
4
8
12 16
Attempted
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b) There is an upward trend. The number of field goals made
increases as the number of field goals attempted increases.
• What is an example of two related sets of
data that show a downward trend? Explain.
(The speed at which a car is travelling and the
amount of time it takes to reach a destination; as the
speed increases, the amount of time decreases.)
• What is an example of two related sets of
data that show no trend? Explain.
(The number of people in the family and the number
of pets; the number of people in a family does not
affect the number of pets the family has.)
Ensure students understand that in a scatter
plot, certain values may have more than one
result. For example, in the scatter plot for Age
and Hours of Sleep in Connect, there are two
points plotted for many of the values for age.
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Unit 5 • Lesson 7 • Student page 196
Practice
Have 1-cm grid paper (PM 23) available for
questions 3 and 5.
Assessment Focus: Question 5
Students use the table of values to draw a scatter
plot. Students may insert scale breaks on both
axes, then start the horizontal axis at 60 and the
vertical axis at 110 and count by 10s. Students
should see an upward trend in the scatter plot,
indicating a relationship between a student’s
age and height.
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4. a) English muffin: 1 g
Wiener: 13 g
Lemon meringue pie: 14 g
b) The red dots tend to be farthest right on the scatter plot.
c) The green dots are closest to the horizontal axis.
d) The points are scattered all over the grid.
5. a)
Height (cm)
Meat or fish
Grain products
No
Age versus Height
180
170
160
150
140
130
120
110
0
60
90
120 150
Age (months)
b) Yes; the youngest age (68 months) and the shortest height
(112 cm) belong to the same ordered pair and are
represented by the same point.
c) Yes; in general, as students get older they get taller.
d) If data for several adults were added to the graph, the
upward trend would level off.
REFLECT: I would expect to see an upward trend between the
amount of time spent studying and the scores on a test. The
greater the amount of time spent studying, the higher the
score. I would expect to see no trend between the number of
letters in a person’s name and test scores.
ASSESSMENT FOR LEARNING
What to Look For
What to Do
Reasoning; Applying concepts
✔ Students understand that a scatter plot
can be used to graph and compare
two sets of numerical data.
✔ Students understand that a scatter plot
shows how two sets of data are related.
Extra Support: Students who have difficulty constructing
scatter plots may benefit from a review of plotting ordered
pairs on a coordinate grid.
Students can use Step-by-Step 7 (Master 5.16) to complete
question 5.
Accuracy of procedures
✔ Students can construct a scatter plot
from a table of values.
✔ Students can make predictions based
on a scatter plot.
Extra Practice: Have students list a few pairs of quantities that
might be represented by each of the three shapes of scatter plots.
Students can complete Extra Practice 3 (Master 5.22).
Extension: Have students use computer software to draw one
of the scatter plots in Practice.
Recording and Reporting
Master 5.2 Ongoing Observations:
Data Analysis
Unit 5 • Lesson 7 • Student page 197
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