Solved: Calculator Issues? Annuity Value at 6 Years w/ 6.8% Compounded Annually

AI Thread Summary
The discussion revolves around calculating the future value of an annuity with annual contributions of $3,000 at a 6.8% interest rate compounded annually over six years. The initial formula used was incorrect due to misplacement of parentheses, leading to an erroneous final amount of $44,103 instead of the correct $21,352. The user realized that the correct expression should have been structured to add 1 to the interest rate before applying the exponent. There was also a discussion on simplifying calculations by avoiding unnecessary divisions and multiplications by 1. Ultimately, the importance of careful formula entry and debugging was emphasized to prevent such errors in future calculations.
yumito
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Homework Statement


To save money you put $3000 at the end of each year in an annuity that pays 6.8% compounded annually. Use the formula for the value of an annuity.
The Given Formula:
Code:
A=P[(1+(r/n)[SUP]nt[/SUP])-1]
     ______________
           (r/n)
How much would be saved at the end of six years.

Homework Equations


The Variables:
Code:
P=3000
R=.068
n=1
t=6
The Completed formula:
Code:
A=3000((1+(.068/1)^(1)(6))-1)
     _______________________
           (.068/1)
When i put this exactly into http://web2.0calc.com/ (because I am without a scientific calculator at the moment)

The Attempt at a Solution



My Final Answer Is: A=44102.945538271292235294118
Rounded To The Nearest dollar: A=$44103
The program I Am Submitting The Answer To Says, the answer is: A=$21352 rounded to the nearest dollar.

My question is why is my answer wrong, is it the calculator? do i have a parentheses out of place?


_____________________________________________________________________________
EDIT: fixed spelling errors and a few minor changes, none involving the math.
 
Last edited:
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after about an hour of crying and an hour of raging that no1 would reply i figured out the mistake it was a parentheses
 
So it was the missing parents around the (1)(6) factor right?
 
nope, it wasn't, even tho that would have been another issue if my post was completely honest i actually multiplied them together before i put it in the calculator, the issue was the (1+(.068/1)^(1)(6)) should have been ((1+(.068/1))^((1)(6)))
 
in other words, add the 1 to the fraction before the exponent
 
yumito said:
...the issue was the (1+(.068/1)^(1)(6))
should have been ((1+(.068/1))^((1)(6)))


What I do to reduce the number of parentheses for that part in the
calculator display and make it relatively easier to read is type:


((1+0.068/1)^(1*6))
 
well from my time spend in my programing classes i must have completely forgotten how to debug, i have become too reliant of others help and need to seriously look at the problem before asking for help. on the most basic level, there are more just remove the outter most set of parenthesis until you see the problem lol
 
checkitagain said:
What I do to reduce the number of parentheses for that part in the
calculator display and make it relatively easier to read is type:


((1+0.068/1)^(1*6))

Why do you show division by 1 and multiplication by 1? Instead of 1 + .068/1, why not write 1.068? And instead of 1*6, why not write just 6?
 
Mark44 said:
Why do you show division by 1 and multiplication by 1?
Instead of 1 + .068/1, why not write 1.068?
And instead of 1*6, why not write just 6?

I was emphasizing an intermediate step where it is common for some beginning
calculator users to enter a product incorrectly. I was allowing for a denominator
other than 1 and a larger product for the exponent by my example.**

For myself, I would actually enter it they way you asked about for
[i[that problem[/i], because I know that is even simpler and I can
do that in my head.



** Example:

P(1 + 0.068/12)^(12*17) is what I would type for a different example
with relatively more difficult arithmetic.
 
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