# Investment rate

• January 27th 2009, 08:54 PM
makaveli89
Investment rate
Karl wants to buy a $800 TV in 21 months. How much should he invest now at 20% simple interest to have the money in 21 months? Investment =$

whatis the necessary equation?

thx
• January 27th 2009, 09:37 PM
(Hi)
Quote:

Originally Posted by makaveli89
Karl wants to buy a $800 TV in 21 months. How much should he invest now at 20% simple interest to have the money in 21 months? Investment =$

whatis the necessary equation?

thx

Interest= (Principal x %Rate per year x Time)/100
Here principal is the amount invested
If your time is in months divide it by 12
Principal + interest = amount ($800) • January 28th 2009, 08:52 AM makaveli89 i don't get it. can u please go more into detail. i tried as equation: 1.2x^1.75 = 800 but it doesnt work, i guess its wrong. • January 29th 2009, 03:14 AM ADARSH I think this might be helpful......... Quote: Originally Posted by makaveli89 Karl wants to buy a$800 TV in 21 months. How much should he invest now at 20% simple interest to have the money in 21 months?
Investment =?

800=Investment+Interest

$Interest=\frac{Investment*21*20}{12*100}$:D
• January 30th 2009, 08:51 PM
makaveli89
i dont know if this makes sense. i have no clue how to solve this
• January 30th 2009, 09:25 PM
1-"Money" has to be invested in the bank to get a profit at the rate of 20% annually this "Money " is called investment and the profit is called interest(Nod) and the value that you need to get is amount (800$) 2- according to your question you need to get 800$ after 21 months at the rate of interest (20% per annum)

3-The formula used here is

$Interest=\frac{Investment*Months*\text {Rate of interest}}{12*100}$

$Amount= Investment+Interest$

(Wait)Now which point you dont get? or is it the fourth option

4)All of these(Bow)
• January 31st 2009, 09:44 AM
makaveli89
what is the final equation?

this one
http://www.mathhelpforum.com/math-he...e06e0d5c-1.gif

which is, 20 = 21*0.2*x / 12*100

????
is that correct because i think its wrong cause the result is not correct.