Question 927754
How long does it take for a sum of money to double itself at a simple interest rate of 10% per annum? 


You presumably know the equation for simple interest calculations :


{{{I =(P * (R/100) * T)}}}


If you want the sum to double, then the interest must equal the principal (P), the amount you started with.

Therefore {{{I = P}}}, hence

{{{I =(P * R * T)}}}, from which

{{{P =(P * 10 * T)/100}}}

{{{100P = P (10) T}}}

.
{{{T =100 P/ 10P=10 years}}}.


example:

 {{{I =P * R * T}}}

let

   {{{ P}}}  be ${{{60.00}}} 
    {{{r }}} be {{{10}}}% per year, or in decimal form, {{{10/100=0.1}}} 
   {{{ t}}} is {{{10}}} years time period 
  

To find the simple interest, we multiply {{{I =P * R * T=60*0.1*10=60}}}

so, the interest is: ${{{60.00}}} which is equal to  the principal amount, and it means our principal amount is doubled