Question 1057528
We'll need the compound interest formula:

   {{{ F = P (1+r/n)^(nt) }}}
—
Where:  
       F = future value (or final value)
       P  = present value
       n = number of compounding periods per year
       r = rate, expressed as a decimal (so 4% is 0.04)
       t = number of years
—

We know:
       P = 20000
       F = 21218
       t = 2 
       n = 1   (compounds once per year)
We need to solve for r

Plugging in these values gives:

     {{{ 21218 = 20000(1+r/1)^(1*2) }}}
     {{{ 21218/20000 = (1+r)^2 }}}
     {{{ 1.0609 = (1+r)^2 }}}     
     {{{ 1.03 = 1+r }}}               ( sqrt of both sides )
     {{{ r = 0.03 }}} 
—
Ans:  r = 3%
—

Check:  {{{ 20000(1+0.03)^2  = 21218 }}}