Algebra 1
You Must Show Work!
Review - Direct Variation
Name:_________________________________
Date:__________________ Period:_________
Review – Linear regression
Homework #36
Given that y varies directly with x, use the specified values to write a direct variation
equation that relates x and y.
1) x = 4, y = 12 ________
2) x = 6, y = -3 ________
Determine whether the equation represents direct variation. IF so, identify the constant
or variation.
3) y = -x __________
__________
6) __________
y
__________
x
4) 4x – 2y = 0 __________
__________
7) __________
___________
y
5) 2x + y = 3 ___________
__________
x
8) y varies directly with x. If x is 40 when y is 80:
a) Write the equation that relates the variables. __________
b) Then find y when x is 60. ___________
9) a) Write a direct variation equation that models the relationship between weight on earth and
weight on the moon for the data.
___________
Weight on the moon (lbs), M
Weight on earth (lbs), E
20
25
30
40
120 150 180 240
b) If you weighed 108 pounds on earth, how much would you weigh on the moon? _________
10) Tell whether the data shows a direct variation. If so, give the constant of variation and
write the equation.
# of Weeks (w)
Money saved in dollars (s)
__________
__________
5
20
10
40
15
60
20
80
__________
11) The weight, W, of a bass fish varies directly with its length, L. A 2-foot bass weighs 6
pounds.
a) Write an equation relating W and L.
__________
b) If a bass fish was 3 feet long, how much would it weigh? __________
For questions 12-15: Use the data below (price of a gallon of gas per week) to answer the
questions.
Week
Price per gallon
1
2
3
4
$1.87 $1.90 $1.95 $1.99
12) Describe the correlation:
5
$2.02
_________________________________
13) Use your calculator to find the equation of the best-fitting line for the data. (Round to
the nearest hundredth where necessary)
____________________________________
14) Predict the price of a gallon of gasoline for week 7. ____________
15) Predict the price of a gallon of gasoline for week 12. ____________
_____ 16) Which equation most closely represents the line of best fit for the data in this table?
A) y 
5
x 3
4
B) y 
4
x 3
5
C) y 
4
x 3
5
D) y 
5
x 3
4
x
Y
1
4
2
6
3
7
4
9
5
10
6
10
______ 17) Which is most likely the equation of the line of best fit for the set of data points.
A) y 
5
x 6
2
B) y 
2
x 6
5
C) y 
2
x 6
5
6
5
D) y 
x 6
2
5
4
3
2
6
1
5
0
5
1
2
3
4
5
6
7
8
9
5
5
_____ 18) Which equation most closely represents the line of best fit for the data in this table?
5
A) y  4 x  5
B) y  x  10
C) y  3x
D) y 
1
x
3
x
y
5
15
6
18
7
21
8
24