Summative Assessment – MAFS.8.F.1.1
1.
Mary is looking at the statements of her cell phone plan from the last 4 months. The relationship of the
additional text messages and the total cost is listed as ordered pairs: (20, 74); (35, 77); (5, 71); (15, 73)
a) What is the independent variable? Additional text messages
What is the dependent variable? Total cost
b) Do the ordered pairs of the cell phone plan represent a function? Justify your answer.
Yes because there is exactly one total cost (output) to each additional text message (input).
c) Which of the following equations could be used to calculate the output by inserting the input?
a. y = .2x + 70
b. y = .1x + 73
c. y = 5x + 60
d. y = x + 65
2.
Suzie is checking the weather forecast for the next 5 days and the temperatures are measured in Celsius:
Monday: 30°C; Tuesday: 45°C; Wednesday: 20°C; Thursday: -5°C; Friday: 0°C
Suzie does not understand Celsius so she needs to convert to Fahrenheit.
a) Calculate to Fahrenheit using this equation:
Input Output
F
9
C  32
5
30
45
20
-5
0
86
113
68
23
32
Monday: 86°F Tuesday: 113°F Wednesday: 68°F
Thursday: 23°F Friday: 32°F
b) Create an input/output table.
c) Does the table represent a function?
Explain your reasoning. Yes because there is exactly one temperature in Fahrenheit (output) to each
temperature in Celsius (input).
3.
Ms. Hall measured the heights of 4 of her students. Two students are 8 years old and one of them is 50
inches tall and the other is 52 inches tall. Another student is 9 years old and is 53 inches tall. The fourth
student is 7 years old and is 48 inches tall.
a) Write the scenario as a list of ordered pairs. (8, 50); (8, 52); (9, 53); (7, 48)
b) Plot and label the ordered pairs on the grid. Label the x and y-axis. Make sure the points are plotted
and labeled correctly. Make sure the x and y-axis are correctly labeled.
c) Use the vertical line test to determine if the graph is a function. Explain why the graph is or is not a
function. The graph is not a function because the vertical line passes through more than one point.
60
50
40
30
20
10
0
0
2
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6
8
10