Question 358978
Reading off from a standard normal table, and using the formula {{{Z = (X - mu)/sigma}}}, we get the system
{{{matrix(2,1, -0.845 = (52.3 - mu)/sigma, 0.525 = (56.3 - mu)/sigma)}}}.
Solving for {{{mu}}} and {{{sigma}}}, we should get
{{{mu = 54.767}}}, and {{{sigma = 2.92}}}.