Download Practice: 8-1 through 8-3 A scientist is studying bacteria in pond

Algebra 2b
Name:
Practice: 8-1 through 8-3
1. A scientist is studying bacteria in pond water. The scientist observes that one cubic
centimeter of pond water contains 1200 bacteria. If the number of bacteria is known to
increase by 12% per day, how many bacteria will there be in one week?
2. Identify if each equation is exponential growth or decay:
3x
y  5 
5 
3 x
y  5
5

y  2401.045


y  0.85 x
x

3. For the equations in question 2, identify (1) the initial value, (2) growth/decay factor
and (3) the percentage of increase/decrease.
4. Consider the function y  21.5  4 .
Identify the parent function, and then describe the transformations that the parent has
undergone to become the given function.
x 2

5. The amount of pollution in Lake Michigan has been decreasing in recent years. Suppose
the amount of fecal colliform bacteria is known to be 3.4 parts per million and is
believed to be decreasing by about 5% per year. Find the amount of this pollutant that
will be present in Lake Michigan in 2020.
6. Write each equation in logarithmic form.
5  125
3

4
3
1 3
   8
2 
1

64


7. Write each equation in exponential form.
log 3 243  5

log 9
1
 2
81
log100000


8. Use your calculator to estimate log150 to 3 decimal places and then explain what you
have just learned.

9. Graph y  3x and its inverse. Then write the equation for its inverse. Then give the
domain and range of each function.
30

25
20
15
10
5
-30
-20
-10
10
-5
-10
-15
-20
-25
-30
20
30