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by ketkoag » Wed May 06, 2009 10:31 am
The annual interest rate earned by an investment increased by 10 percent from last
year to this year. If the annual interest rate earned by the investment this year was 1
percent, what was the annual interest rate last year?
A. 1% B. 1.1% C. 9.1% D. 10% E. 10.8%

i got [spoiler].909%[/spoiler] . please lemme know if u get the same answer or explain what i did wrong..
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Source: — Problem Solving |

by vitaly » Wed May 06, 2009 11:57 am
Yes, you're correct. I calculate it this way:

1 - 110%
x - 100%

-> x = 1*100/110 = 10/11 = 0.909 ~= 0.91

So, answer seems to be C.
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by ketkoag » Thu May 07, 2009 10:26 am
but C is 9.1% not .91% !!
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by DeepakR » Thu May 07, 2009 6:14 pm
I too get the same as 0.9%

Let annual interest rate for last year = x %
This year it has increased by 10%= (x/100) + (x/100)*(10/100)
=11x/1000 -------A

Given that it was 1% this year, hence 1/100=11x/1000 hence x=10/11=0.909%

-Deepak
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