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`Adding NAU problems to the NPL`

```    1 ##DESCRIPTION
2 ## DBsubject('Algebra')
3 ## DBchapter('Exponential and Logarithmic Functions')
4 ## DBsection('Exponential and Logarithmic Equations')
5 ## KEYWORDS('word problem')
6 ## Author('Katie Louchart')
7 ## Institution('NAU')
8 ##ENDDESCRIPTION
9
10 # File Created: 8/9/05
11 # Location: Northern Arizona University
12 # Course: Precalculus
13
14 DOCUMENT();
15
17 "PG.pl",
18 "PGbasicmacros.pl",
19 "PGchoicemacros.pl",
21 "PGauxiliaryFunctions.pl",
22 "PGasu.pl",
24 );
25
26 TEXT(beginproblem());
28
29
30 \$a=random(3,6, .01);
31 \$b=random(35,75,5);
32 \$c=\$a/100;
33 \$ans=log(\$b/100)/(-\$c);
34
35 BEGIN_TEXT
36 In a certain country, the rate of deforestation is about \$a\$PERCENT per year.  Assume that the amount of forest remaining is given by the function
37 \$PAR
38 \( F = F_0 e^{-\$c t} \)
39 \$BR
40 \$BR
41 where \( F_0 \) is the present acreage of forest land and \( t \) is the time in years from the present.  In how many years will there be only \$b\$PERCENT  of the present acreage remaining?
42 \$BR