Answers to Selected Exercises 547Exercises 3.3 Population Models
- P(t) = (2.5 x 108 )10 '3~~
50
where t is the calendar year. 2250. - 2.1 x 108 people= 210 million people
year 1800 1810 1820 1830 1840 1850 1860 1870 1880 1890 1900
prediction 5. 31 7.19 9.71 13.05 17.43 23.09 30 .28 39.21 49 .99 62.55 76.63- a. limt_,+ 00 P(t) appears to approach approximately 450.
b. limt_,+ 00 P(t) appears to approach approximately 300.
c. limt_,+ 00 P(t) = 0.- a. P(t) decreases. b. P(t) increases.
Exercises 3.4 Simple Epidemic Models
- a. Duration t ~ 9.84; I(t) ~ 205
b. Duration t* ~ 8.48; I(t*) ~ 76Exercises 3.5 Falling Bodies
1. dv / dt = g - cv^2.
3. dv/dt=g-c,jV.
Terminal velocity ~ 11.31 ft/sec.No terminal velocity.Exercises 3.6 Mixture Problems
- About 3.7 sec 3. 10.4 years, 17.3 years, 26 .3 years
Exercises 3. 7 Curves of Pursuit
- a. The boat lands .25 miles below the man.
b. and c. The boat lands at the man.