Question 429430
{{{mu = 4}}}
==> {{{P(X < 5.76) = 0.72}}}
==> {{{P((X - 4)/sigma < 1.76/sigma) = 0.72}}}
==> {{{1.76/sigma = 0.58}}}, approximately.
==> {{{sigma = 3.0345}}}, to 4 decimal places.