In: Math
a) The number of voices I hear at 7am is 12000 at 9am the count is 36000, if the number of voices grows exponentially, find the time it takes to reach 81000 voices?
b) assume one voice tells me to invest 20000 in a south american bank where the interest is compounded continiously, after 6 years i have 24000 dollars, what must the interest rate have been?