Question

invests $5,000 in an account that pays 6.25% interest per year. After how many years will her investment be worth $10,000?

Answer 1

sounds like a simple interest problem

the formula for simple interest is

I = Prt
in this case P is $5,000; r is 0.0625; I is $10,000 and you're looking for t so just substitute
\[\implies 10,000 = (5,000)(0.0625)t\]
divide both sides by 5,000
\[\implies 2 = 0.0625 t\]
divide both sides by 0.0625
\[\implies 32 = t\]
does that help?

Answer 2

i got 13.7?

Answer 3

how did you get that?

Answer 4

i showed you how to do it. where did you go wrong?

Answer 5

http://finedrafts.com/files/Larson%20PreCal%208th/Larson%20Precal%20CH1.pdf

Answer 6

Oh no no..i there's a mistake..
IIRC this is the formula:
\[A_n = P\left(1+\frac{r}{100}\right)^{n} \]
where r(rate) = 6.25 , n= n , P = 5000, A_n = 10 000

Answer 7

so you're finding n which is the year

Answer 8

that's for compound interest @Mimi_x3

Answer 9

Compound interest is found by \(A_n - P\)

Answer 10

well i havent done these in a while tho :/

Answer 11

it's okay @Mimi_x3

page 222 and here's a little chapter

http://finedrafts.com/files/Larson%20PreCal%208th/Larson%20Precal%20CH3.pdf

Answer 12

hmm..looks like i have to look back at my notes..

how can you tell the differennce if its simple interest and compound interest? :/

Answer 13

simple interest only allows the principal to accrue by the term, that is the n year(s) or month(s)

compound interest is better understood this way:
let us say you are given a choice to pick between 1 million dollars or 1 cent and is doubled every day for the next 30 days, which one would you pick?

Answer 14

oohh..i got it..because the 5k does not double up or anyother words you only invest 5k..i made a mistake then sorry

Answer 15

here's why banks can rip you off
http://www.al6400.com/blog/2006/07/10/a-penny-doubled-everyday/

Answer 16

14.1??