Question 43876
My logs are to base 10:


{{{ 3.9^(m-4)=10.21 }}}
{{{ (m-4)log(3.9) = log(10.21) }}}
{{{ (m-4) = (log(10.21))/(log(3.9)) }}}
m-4 = 1.70713274
m = 5.70713274
m = 5.7071 to 4dp


jon.