MA 15900
EXAM
3
FALL 2009
1
1. Find the exact value of
cos
−
9
π
4
.
1)
3
−
1
2)
1
−
3
3)
−
1
3
−
1
4)
1
3
−
1
5)
−
2
6)
2
7)
−
2
2
8)
2
2
9) None of the above
2. Solve the following equation.
log
3
(
x
+
2)
+
log
3
x
=
log
3
15
1)
x
=
−
15
7
2)
x
=
1
7
3)
x
=
−
15
7
,
1
7
4)
x
=
3
2
5)
x
=
13
2
6)
x
=
3
2
,
13
2
7)
x
=
−
5
8)
x
=
3
9)
x
=
−
5,3
3. After an amount of a drug is injected into a body, the drug is then eliminated from the body over time.
Suppose that for an initial dose of 20 milligrams, the amount
A
(
t
) in the body
t
hours later is
given by
A
(
t
)
=
20(0.7)
t
. After 3 hours have passed since the injection, what percentage of the
initial dose will have been
eliminated
?
1)
6.86%
2)
10%
3)
14%
4)
34.3%
5)
65.7%
6)
86%
7)
90%
8)
93.1%
9) None of the above

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