Question 869231
z = (x-mu)/sigma
z = (4.1-3.1)/0.5
z = 1/0.5
z = 2



Now use a <a href="http://www.math.upenn.edu/~chhays/zscoretable.pdf">table</a> to find the area to the left of z = 2. This is approximately 0.9772 (roughly 97.72%)


So you are correct. The only typo you made was writing {{{(x-mean)/(standard deviation/square root of n)}}} when you should have written {{{(x-mu)/sigma}}}


{{{mu = mean}}} (greek letter lowercase mu)
{{{sigma = standard_deviation}}} (greek letter lowercase sigma)