# Pert and Ab^t form

• Dec 11th 2009, 05:05 PM
mathcalculushelp
Pert and Ab^t form
Below gives values of an exponential function P.Give a formula P(t) in the form P(t)=Poa^t and also in the form P(t)=Poe^rt.If rounding is necessary round to 4 decimal places.

t | 0| 1 | 2
P(t)| 60 | 94.8 | 149.784
• Dec 11th 2009, 06:13 PM
dedust
$\displaystyle P(t)=P_{0}a^t$, subs $\displaystyle t=0$, we get $\displaystyle P_{0}=60$. subs $\displaystyle t=1$, you'll get $\displaystyle a$.

for $\displaystyle P(t)=P_{0}e^{rt}$, subs $\displaystyle t=0$ and $\displaystyle t=1$ (or $\displaystyle t=2$) you'll get $\displaystyle P_{0}$ and $\displaystyle r$
• Dec 14th 2009, 11:40 AM
mathcalculushelp
finding r
For
P(t)=Poe^rt

am putting t=0
so Po=60

how do i get r?

once i get Po and r ..do i plug it in the formula?
• Dec 14th 2009, 12:51 PM
e^(i*pi)
Quote:

Originally Posted by mathcalculushelp
For
P(t)=Poe^rt

am putting t=0
so Po=60

how do i get r?

once i get Po and r ..do i plug it in the formula?

You shouldn't use that point because for t=0: $\displaystyle e^{rt} = e^0 = 1$

Instead use the next point at t=1

$\displaystyle r = \frac{1}{t}(ln[P(t)]-ln[P(0)])$