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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 />

© Houghton Mifflin Company. All rights reserved.

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