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Suppose you deposit 900 dollars into a bank with 5% simple interest. The amount in the account after t years is given by A(t)=900(1.05)t (in dollars).
1. What is the average rate of change for the first year? Rate (in dollars per year): 900(1.05)-900
2. What is the average rate of change for the first five years? Rate (in dollars per year):
3. What is the average rate of change for the first ten years? Rate (in dollars per year):
4. Does the average rate of change increase or decrease as time from the initial deposit gets longer?


Sagot :

Answer:

1. 45 dollars per year.

2. 49.73 dollars per year.

3. 56.6 dollars per year.

4. Increases

Step-by-step explanation:

Average rate of change

The average rate of change of a function [tex]f(x)[/tex] over an interval [a,b] is given by:

[tex]A = \frac{f(b)-f(a)}{b-a}[/tex]

In this question, we have that:

[tex]A(t) = 900(1.05)^t[/tex]

1. What is the average rate of change for the first year?

[tex]A(0) = 900(1.05)^0 = 900[/tex]

[tex]A(1) = 900(1.05)^1 = 945[/tex]

So

[tex]A = \frac{A(1)-A(0)}{1-0} = \frac{945-900}{1-0} = 45[/tex]

45 dollars per year.

2. What is the average rate of change for the first five years?

[tex]A(0) = 900(1.05)^0 = 900[/tex]

[tex]A(5) = 900(1.05)^5 = 1148.65[/tex]

[tex]A = \frac{A(5)-A(0)}{5-0} = \frac{1148.65-900}{5-0} = 49.73[/tex]

49.73 dollars per year.

3. What is the average rate of change for the first ten years?

[tex]A(0) = 900(1.05)^0 = 900[/tex]

[tex]A(10) = 900(1.05)^{10} = 1466[/tex]

[tex]A = \frac{A(10)-A(0)}{10-0} = \frac{1466-900}{10-0} = 56.6[/tex]

56.6 dollars per year.

4. Does the average rate of change increase or decrease as time from the initial deposit gets longer?

From the previous items, it increases.