8th Grade Benchmark 3 Review 2015
ANSWER KEY
1. Does the scatter plot show a positive correlation, negative correlation, or no correlation?
No Correlation
Positive Correlation
2. If one is not given, sketch a line of best fit for the scatter plot. Then write an equation (in slope-intercept
form) for the line of best fit.
Equation: y=2x + 20
Equation: y=20x + 0
Mrs. Doughty has 20 years’ experience.
What is her income? 50
3. Find the slope of a line that goes through the given points.
a.
(3, 5), (3, 9)
Undefined
b. (0, 3), (-2, -9)
6
c. (4, 10), (2, 15)
5/-2
d. (7, 8), (-9, 8)
0
4. The graph of a line passes through the points (0, 4) and (2, 10). Write an equation of the line in slopeintercept form.
Y=3x+4
5. Find the slope of each line.
a
a. Undefined
d
c
b
b. 2
c.-2/3
d.3
6. Write the equation (in slope-intercept form) for each line shown.
Equation: y=2x-2
Equation: y=1x+0
Equation: y=-1/2x+2
7. Identify each equation as linear or nonlinear.
a.
y  12 x  6
Linear
6
 10
x
b. 5 x  y  10
c. y  5 x 2  1
d. y =
linear
nonlinear
nonlinear
8. Identify each graph as linear or nonlinear. Linear equations must make one straight line
a.
b.
c.
Nonlinear
Linear
Nonlinear
Distance from home
9. Which story matches the time and distance graph at the right?
a. Sam left his friend’s house and rode his bike further
away from home. He stayed away for a while and then
rode back to his house.
b. Sam left his house to visit his friend. He and his friend
ran along the rode and then ended back at Sam’s house.
c. Sam was at his friend’s house. He started walking
home, but stopped and visited with a friend he saw.
Then he continued on to his house.
Time
10. Change the word sentence into a mathematical equation. Tell what each variable represents.
A cell phone bill costs $50 per month plus $0.05 per text message.
a.
b.
c.
d.
C = 0.05 + 50n
n = 50 + 0.05C
C = 50 + 0.05n
C + 50 = 0.05n
C
C
C
C
=
=
=
=
total
total
total
total
cost;
cost;
cost;
cost;
n
n
n
n
=
=
=
=
number
number
number
number
of
of
of
of
text
text
text
text
messages
messages
messages
messages
11. The total cost of a banquet is $300 plus $5 for each person who attends. Write an equation to represent
the total cost of a banquet. Then find the total cost if there were 50 people in attendance.
Let:
T = total cost
p = number of people attending
Equation: y=5x +300 or T=5p+300
It would cost $550 if 50 people attended
12. Which of the following graphs matches the story below?
Distance from
home
Distance from
home
Mary rode her bike from her aunt’s house towards home. She rode very fast for a while and then
slowed down. Then she just cruised along for a while, never quite making it to her house.
Time
Distance from
home
Distance from
home
Time
Time
Time
13. Determine the rate of change and initial value of the function shown in the table below.
x
y
Rate of change -2/1
-2
10
-1
8
0
6
1
4
2
2
initial value 6
14. Mrs. Dunn drove 35 miles in 30 minutes. If she continues at this rate for 2 hours, what is her rate of
change?
35/30 which reduces to 7/1 so Mrs. Dunn travels seven miles every minute
15. Mrs. Powell spends $100 a month on a new purse. She earns $3,000 a month. Determine the slope and
y-intercept. Then write an equation representing this situation (in slope-intercept form, of course!).
Slope -100
Y-intercept 3000
Equation y= -100x + 3000
16. Use the table above to answer the following questions:
a. How many more males prefer sports car than an SUV? Show or explain your work.
18 (subtract male sports car from male suv)
b. How many males and females prefer a sports car? Show or explain your work.
84 (look at the total underneath sports car)
17. Mr. Clapper earns extra money by doing odd jobs for neighbors. He charges a flat fee plus a certain
amount per hour for each job. He wrote the equation c = 8j + 15 to predict c, the total amount he will earn.
What could the numbers 15 and 8 represent in his equation?
8 is how much he charges per hour
15 is the flat fee he gets paid no matter what
18. Which statement about the slopes of the functions below is true?
Function A
y = -3x + 5
A.
B.
C.
D.
Function B
x
2
4
6
8
y
-8
-9
-10
-11
The slopes of both functions are negative.
The slopes of both functions are positive.
The slope of function A is negative and the slope of function B is positive.
The slope of function A is positive and the slope of function B is negative.