Answer :
14.71 years when simple interest used annually.
10.59 years when compounded Interest used annually.
We can calculate the doubling time by either using simple interest rate annually or compounded interest rate annually.
First, if we use simple interest rate annually than according to the formula it can be derived simply by dividing the periodic rate by 1.
Doubling Time without compounding = 1/rate.
= 1/6.8
= 14.71 years when simple interest
used annually.
In case of compounded interest rate annually.
Doubling time through Rule of 72 is by dividing 72 by the interest rate.
= 72/6.8
10.59 years when compounded annually.
However, if we use normal excel calculations then
For simple interest time required to double the money let say $100.
A = PRT+P
200 =100×6.8×T+100
100 =6.8T
T =14.71 years
For compounded interest
A = P[tex](1+r)^n[/tex]
200 = 100[tex](1+6.8)^n[/tex]
2 =[tex]1.068^n[/tex]
n = 10.54 years
Learn more about simple interest, here
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