1.
If
y
varies jointly as the square of
x
and the cube of
z
and
y
= 9 when
x
= 3 and
z
= 4, find
y
when
x
= 8 and
z
= 5.
A.
45
B.
125
C.
100
D.
40
Hint
2.
Suppose
y
varies directly as
x
and
y
= 13 when
x
= 7. Find the constant of variation and write an equation.
A.
k
=
and
y
= 13 · 7
x
B.
k
=
and
y
= 13 · 7
x
C.
k
=
and
y
=
x
D.
k
=
and
y
=
x
Hint
3.
If
y
varies inversely as the cube of
x
and
y
= 8 when
x
= 2, find
x
when
y
= 1.
A.
x
= 8
B.
x
= 1
C.
x
= 2
D.
x
= 4
Hint
4.
Which best describes this graph?
A.
none of these
B.
direct variation
C.
joint variation
D.
inverse variation
Hint
5.
Dakota wants to cook a meal for his family. He knows that the more people who help, the less time it will take to prepare the food. Write an equation that represents this situation. Let
C
be the cooks in the kitchen,
T
be the time and
k
as the constant of variation.
A.
k
=
CT
B.
T
=
kC
C.
k
=
C
T
D.
C
=
kT
Hint