5 SD's
Dear Unlucky,
I guess no one is going to tell you so I might as well, My first assessment is (In order of Probabilitys) that:
1) You didn't calculate the Standard Deviations properly iff (if and only if) this is not true "THEN".
2) The post contains intentional non truths for some psychological reasons,"OR"
3)You do not understand how to read the BS chart
4) "OR" do not understand how to implement the strategy
5)"OR" are deviating from the strategy on hunches (gambling).
6) "OR" are being deceived (cheated) by the casino.
7) "OR" are experiencing the extremes of probability.
Notice the conclusion you drew was one of the last choices, Understand that this is not a scientific assessment only a practical theorem of the case in question.