Name: __________________________________________
Int Math 3 Notes (Sec.5-4)
Is the relationship between the variables in the table a direct variation, an inverse
variation, or neither? If it is a direct or inverse variation, write a function to model it.
1
x
–2
0
1
5
y
36
0
–18
–90
4
Suppose that x and y vary inversely, and x =
10 when y = 4. Write the function that models
the inverse variation.
5
Suppose that m and r vary inversely and that
5
r =
when m = 10. Write a function that
6
models the inverse variation and find r when
m = 3.
direct variation; y = −18x
−72
inverse variation; y =
x
neither
A
B
C
2
x
4
9
13
14
y
6
23
26
38
3
x
7
8
13
18
y
44
51
86
121
1
Name: ______________________
6
A drama club is planning a bus trip to New York City to see a Broadway play. The table represents the
cost per person for the bus rental compared to the number of people going on the trip. What function
models the data, and how much per person will it cost if 12 students go on the trip?
Number of Students (n)
Cost per Student (c)
A
B
7
3
$24
n
= 9, $12
c
n
= 72, $12
c
6
$12
9
$8
C
nc = 9, $10
D
nc = 72, $6
16
$4.5
A soccer team is collecting money to buy their coach a present. The table represents the cost per
person for the gift compared to the number of people contributing. What function models the data, and
how much per person will it cost if all 40 players contribute?
Number of Players
(n)
Cost per Player (c)
8
ID: A
5
8
15
20
$40
$25
$13
$10
Suppose that y varies directly with x and
inversely with z, and y = 36 when x = 20 and
z = 5. Write the equation that models the
relationship. Then find y when x = 32 and z =
8.
9
2
Suppose that y varies jointly with w and x and
inversely with z and y = 96 when w = 8, x =
32 and z = 8. Write the equation that models
the relationship. Then find y when w = 2, x = 2
and z = 3.
Name: ______________________
ID: A
10 Designer Dolls, Inc. found that the number N of dolls sold varies directly with their advertising budget A
and inversely with the price P of each doll. The company sold 7600 dolls when $36,000 was spent on
advertising and the price of a doll was set at $35. Determine the number of dolls sold when the amount
spent on advertising is increased to $58,000. Round to the nearest whole number.
11 The amount of oil used by a ship traveling at a uniform speed varies jointly with the distance and the
square of the speed. The ship uses 31 barrels of oil in traveling 80 miles at 31 mi/h. How many barrels
of oil are used when the ship travels 34 miles at 54 mi/h? Round your answer to the nearest tenth of a
barrel, if necessary.
3