College Algebra
Answer/Discussion to Practice Problems Tutorial 42: Exponential Functions
Answer/Discussion
to 1a

Try this using your calculator and see if you get the answer that I
got. If you didn't, refer back to e key on calculator that I have above. 
Answer/Discussion
to 1b

Try this using your calculator and see if you get the answer that I
got. If you didn't, refer back to e key on calculator that I have above. 
Answer/Discussion
to 2a

Note that the base = 5 and the exponent is our variable x +
1. There is one outside factor, we are adding 1 to our variable x in the exponent 
Answer/Discussion
to 2b

Note that the base = 1/5 and the exponent is our variable x.
There are 2 outside factors, we are multiplying it by 5 AND we are
adding 2 to our base after we raise it to the exponent x and multiply that by 5. 
Answer/Discussion
to 3a
$7500 for 25 years at an annual rate of 4.25% compounded monthly. 
P = 7500
r = 4.25% = .0425
t = 25
n = monthly = 12 times a year 

*Plug in values shown above into compound form.
*Find number inside the ( ) first
*Raise the ( ) to the 300th power
*Multiply 
So the compound AMOUNT would be $21661.27
The compound amount is the total amount that is in the account. How
do you think we are going to get the interest?? Well we have the principle
which is the beginning amount and we have the compound amount which is
the end result. Looks like, if we take the difference of the two, that
will give us how much interest was earned from beginning to end. What do
you think?
Compound amount  principle: 21661.27  7500 = 14161.27
So our compound interest is $14161.27 
Answer/Discussion
to 3b
$3000 for 20 years at an annual rate of 6% compounded quarterly. 
P = 3000
r = 6% = .06
t = 20
n = quarterly = 4 times a year 

*Plug in values shown above into compound form.
*Find number inside the ( ) first
*Raise the ( ) to the 300th power
*Multiply 
So the compound AMOUNT would be $9871.99
The compound amount is the total amount that is in the account. How
do you think we are going to get the interest?? Well we have the principle
which is the beginning amount and we have the compound amount which is
the end result. Looks like, if we take the difference of the two, that
will give us how much interest was earned from beginning to end. What do
you think?
Compound amount  principle: 9871.99  3000 = 6871.99
So our compound interest is $6871.99 
Answer/Discussion
to 4a
$8000 that is compounded continuously for 10 years at an interest rate
of 5.5%. 
P = 8000
r = 5.5% = .055
t = 10 

*Plug in values shown above into compound
form.
*Raise e to the
.55th power
*Multiply

So the accumulated or compound AMOUNT would be $13866.02. 
Last revised on March 17, 2011 by Kim Seward.
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