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Simple Interest

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Simple Interest

by sampath » Fri Aug 19, 2011 1:50 am
Someone invested x dollars at simple annual interest, and the investment, including interest will be doubled in 8 and 1/3 years. What will be the total amount of the investment after 25 years?

OA given is 4X
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by Anurag@Gurome » Fri Aug 19, 2011 3:18 am
sampath wrote:Someone invested x dollars at simple annual interest, and the investment, including interest will be doubled in 8 and 1/3 years. What will be the total amount of the investment after 25 years?
Interest of x dollars in 8 and 1/3 years, i.e. 25/3 years = (2x - x) = x dollars

Hence, interest of x dollars in 25 years = 3*x dollars

Therefore, total amount of the investment after 25 years = (x + 3x) = 4x dollars
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by alaynaik » Fri Aug 19, 2011 3:35 am
I reckon the solution is as follows:

From the formula of SI,

Total amount = P + PRN/100

So, total amount at the end of 8 & 1/3 years will be: 2x = x + (x*r*100/12*100)[ 8 & 1/3 years = 100 months and 12 in the denominator because 12 months in a year]

Solving the equation we get, r = 12%.

Now, for total amount after 25 years,

Total amount = x + (x*12*25)/100.

Upon solving we get, total amount = 4x.

Hope this helps.

Thanks

2x = x + (x*r*n)/100
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