Question 1040411
1. n(t)=18000e^0.07t
22,000=18000e^0.07t
divide both sides by 18000
22/18=e^0.07t=11/9
Take ln of both sides, because ln reverses e.  ln *e^0.07t=0.07t.  The e disappears
ln(11/9)=0.07t.  Divide everything by 0.07 and then round at the end.
t=2.9 years
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check with 3 years, which should be more:  18000*e^(0.21)=22206
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2.  t=-10 ln(t-70)/(98.6-70)
t=-10 ln(93.4-70)/28.6=-10(ln(23.4)/28.6=-10*(-0.200)=2 hours
t=-10ln(89.2-70)/28.6)=-10ln(19.2/28.6)=3.98 hours.
Time of death was 7 a.m. This is consistent with the 9 a.m. and 11 a.m. temperatures.