1.
If
y
varies directly as the cube of
x
and
y
= 30 when
x
= 2, find
x
when
y
= 468.75.
A.
3
B.
9
C.
5
D.
7
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
=
x
B.
k
=
and
y
= 13 · 7
x
C.
k
=
and
y
= 13 · 7
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
= 2
B.
x
= 4
C.
x
= 8
D.
x
= 1
Hint
4.
If
y
varies jointly as
x
and the cube root of
z
,
and
y
= 30 when
x
= -5
and
z
= 27, find y when
z
= -8 and
x
= 0.5.
A.
y
= -2
B.
y
= 2
C.
y
= 4
D.
y
= 20
Hint
5.
Which best describes this graph?
A.
none of these
B.
direct variation
C.
inverse variation
D.
joint variation
Hint