Answer
12000 dollars
$r = \frac{\sqrt 30}{5} -1$
Work Step by Step
The formula for interest is
$r = \sqrt \frac{A}{P} -1$
We substitute A= 12000 because we want to make 2000 interest. And P= 10000
$r = \sqrt \frac{12000}{10000} -1$
The square root of 10000 us 100 because 100 x 100 = 10000
$r = \frac{ \sqrt 12000}{100} -1$
We can rewrite the $\sqrt 12000$ as $\sqrt 400$ and $\sqrt 30$ because 400 and 30 are factors of 12000.
$r = \frac{ \sqrt 400 \sqrt 30}{100} -1$
The square root of 400 is 20 because 20 x 20 = 400
$r = \frac{ 20 \sqrt 30}{100} -1$
We divide 20 by 100 and get 1 divided by 5
$r = \frac{\sqrt 30}{5} -1$
