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246 Chapter 3 Exponential and Logarithmic Functions<br />
34. Let t 0 correspond to 2005.<br />
(a)<br />
(b)<br />
V mt b, V0 1150 ⇒ b 1150<br />
V2 550 ⇒ 550 m2 1150 ⇒ m 300<br />
Vt 300t 1150<br />
V ae kt , V0 1150 ⇒ a 1150<br />
V2 550 ⇒ 550 1150e 2k<br />
⇒ k 1 2<br />
Vt 1150e 0.3688t<br />
ln<br />
55<br />
115 0.3688<br />
(c)<br />
1200<br />
0 10<br />
0<br />
(d) The exponential model depreciates faster in the<br />
first year.<br />
(e) Answers will vary.<br />
35.<br />
St 1001 e kt 36.<br />
(a)<br />
(b)<br />
(c)<br />
15 1001 e k1 <br />
85 100e k<br />
St 1001 e 0.1625t <br />
100<br />
0<br />
0<br />
k ln 0.85<br />
k 0.1625<br />
50<br />
S5 1001 e 0.16255 <br />
55.625 55,625 units<br />
S 101 e kx <br />
x 5 in hundreds<br />
S 2.5 in thousands<br />
(a) 2.5 101 e k5 <br />
0.25 1 e 5k<br />
e 5k 0.75<br />
5k ln 0.75<br />
k 0.0575<br />
S 101 e 0.0575x <br />
(b) When x 7, S 101 e 0.05757 3.314<br />
which corresponds to 3314 units.<br />
37.<br />
y 0.0266e x1002 450 ,<br />
70 ≤ x ≤ 115<br />
38.<br />
y 0.7979e x5.42 0.5<br />
(a)<br />
0.05<br />
(a)<br />
1<br />
70<br />
0<br />
(b) Maximum point is x 100, the average<br />
IQ score.<br />
115<br />
4<br />
0<br />
(b) About 5.4 hours<br />
7<br />
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