Split - New Car

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fellow

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May 29, 2013
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A new car sold for$31000. If the vehicle loses 15% of its value each year, how much will it be worth after 10 years?
Using a=31000, r=0.15 and n=10 in a x r^0.15 the answer is no where near $6103.11. Do I need another formula, or I'm not thinking right.
 
fellow said:
A new car sold for$31000. If the vehicle loses 15% of its value each year, how much will it be worth after 10 years?
Using a=31000, r=0.15 and n=10 in a x r^0.15 the answer is no where near $6103.11. Do I need another formula, or I'm not thinking right.
Click to expand...

Please start a new thread for each question.

Now that that is out of the way, do you know the formula for the sum of n terms of a geometric sequence?
 
Yes, that's the wrong formula.

Important: Please do not use the letter x as a multiplication symbol, anymore. Beginning with algebra, the letter x represents a numerical value, not an operator. Use an asterisk to show multiplication, instead.

You wrote r=0.15, and then you wrote r^0.15

After assigning the value 0.15 to the symbol r, subsequently writing r^0.15 means 0.15^0.15. That's not correct.

a*(1-r)^n is the correct formula.

Cheers :cool:
 
fellow said:
Yes Sn=1-r^n ÷1-r
Click to expand...
The expression on the right-hand side of the above equation could mean either of the following:

. . . . .\(\displaystyle \displaystyle{1\, -\, r^{\frac{n}{1}}\, -\, r}\)

. . . . .\(\displaystyle \displaystyle{1\, -\, \frac{r^n}{1}\, -\, r}\)

But I have a feeling that neither of these is correct. I suspect that you meant something more like this:

. . . . .\(\displaystyle \displaystyle{\frac{1\, -\, r^n}{1\, -\, r}}\)

However, without grouping symbols, there is no mathematical justification for my suspicion! ;)
 
If the value decreases by 15% each year, then each year it is worth 100- 15= 85% of the value the year before. Use r= .85. Try 31000(.85^{10})
 
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