What does it mean wiun Something aows of daays exponen nally
Solution
Many real world situtaions can be modelled as exponentila growth or decay such as:
studies of populations, bacteria, the AIDS virus, radioactive substances, electricity, temperatures , bank credits etc
Exponential growth or decay means the quantity is varying exponentialy:
y(t) = a*ekt
y(t) = value at time \"t\"
a = value at the start
k = rate of growth (when >0) or decay (when <0)
t = time
example : 3 years ago you had $ 100 in the bank. You now have $192.
If the amount of money at the end of each year increases exponentially, then how much will you have in the bank after another 7 years?
tart with the formula y(t) = aekt
We know y(0) = 100
100 = ae0
a = 100
We also know y(3) = 192
192 = 100e3k
e3k = 192 ÷ 100 = 1.92
3k = ln(1.92) = 0.652...
k = 0.652... ÷ 3 = 0.217...
Now we know a and k, we can write the growth function y(t) = aekt explicitly as
y(t) = 100e0.217t
Now, we can find how much money there will be in the bank after a further 7 years by replacing t with 10:
y(10) = 100e0.217 × 10
= 100e^2.17
= 100 × 8.758...
= 875.8
You will have $875.8 in the bank after a further 7 years
