1. 7.3B Applications of Solving Exponential Equations
a is the initial amount
b is the growth factor
t is time (years, months, days, hours)
p is the time for one period
Math 30-1

2. Application of Exponential Growth
A cell doubles every 4 min. If there are 500 cells originally,
how much time would pass when they reached cells?
Therefore, it would take
20 min for the cells to
reach
t = 20
Math 30-1

3. Radioactive materials decay in an exponential manner.
Applications of Exponential Equations
Radioactive materials decay in an exponential manner.
If Radon has a half life of 25 days, how long
would it take a 200 mg sample to decay to 12.5 mg?
It takes 100 days for the sample to decay to 12.5 mg.
Math 30-1

4. Applications of Exponential Equations
A bacterial culture doubles in size every 25 minutes. If a population starts with 100 bacteria, then how long will it take the population to reach ?
It would take the bacteria 350 minutes or approximately 5.83 hours to reach a population of
Math 30-1

5. Applications of Exponential Equations
Cobalt-60 which has a half-life of 5.3 years, is used extensively in medical radiology. The amount left at any given time is given by:
a) What fraction of the initial amount will be left after 15.9 years?
b) How long will it take until there is only 6.25% of the original amount left?
Math 30-1

6. If S4000 is invested in an account paying 0
If S4000 is invested in an account paying 0.03% daily interest compounded daily, what is the balance after 7 years?
Determine how long $1000 needs to be invested in an account that earns 8.3% per year, compounded semi-annually before it increases in value to $1490.
Must round to 5 years
Math 30-1

7. Assignment
Page 364
8, 9, 10, 11, 12, 13, 14
Math 30-1