Question 982542
The time it takes to double the balance in an account varies inversely with the interest rate.
 If you invest $1000 at 6% it will take 12 years to double your money.
 Find the time it will take to double your money at 4%.
:
let t = time to double at 4%
:
An inverse relationship equation between the interest and the time to double
{{{t/12}}} = {{{6/4}}}
cross multiply
4t = 12 * 6
4t = 72
t = 72/4
t = 18 yrs to double at 4%