Is that 6%/year simple interest? If so, then

Question

$500 x 0.06 = $30 for one year. So for 90 days, $530 can't be correct. I would like to have an account that would more than double in a year, much less in 90 days.

The Investors Club invests $500 at 6%
simple interest. How much is in the account after 90 days?

I get $530- Can you check

Is that 6%/year simple interest? If so, then
$500 x 0.06 = $30 for one year. So for 90 days, $530 can't be correct. I would like to have an account that would more than double in a year, much less in 90 days.