Remark
This problem is done in 2 steps. The first step determines k and the second step is your answer.
Determining K
P = 233 million
A = 231 million
k = ??
t = 1999 - 1991 = 8 years.
Solution
P = Ae^(kt)
233 = 231 * e ^(kt) Divide by 231
233/231 = e^(k8) Do the division
1.008658 = e^(k8) Take the log of both sides.
ln(1.008658) = k8 * ln(e) You are in natural logs. Ln(e) = 1; kt can be brought down and made into a result that is multiplied by ln(e)
ln(1.008658) = 8k Take the ln of 1.008 ...
0.008621 = 8k Divide by 8
k = 0.008621 / 8
k = 0.0011 rounded, but a more accurate number is in the storage area of the calculator.
Now to get the second part.
P = ??
A = 231
k = 0.0011
t = 12
P = 231 * e^(0.0011*12)
P = 231 * e^(0.012931114) using the stored value of M
P = 231 * 1.013015083
P = 234.006 which rounded to the closest million is 234 million
Answer 234 million.
