You have $100$ returns that have a mean of $2\mathrm{.}40\%$ and a standard deviation of $6\mathrm{.}6545\%.$ If $90\%$ of actual returns are at or below $+8\mathrm{.}00\%$ what is the absolute difference between the actual cumulative probability and the theoretical cumulative probability?

Type in your answer with the right sign as a decimal, rounded it off to $4$ decimal places.