Posted by Andy G on .
In a savings account, a principal of $1000 is deposited at 5% per annum. In the second account a principal of $500 is deposited at 10% per annum. Both accounts are compounded continuously.
a. estimate the doubling time for each

interest 
Reiny,
we don't really need the amount
at first rate:
2 = 1 e^(.05t)
ln2 = .05t
t = 13.86 > the doubling time
at 2nd rate:
2 = 1 e^(.1t)
you finish it.