John10

Thanks amalj
@mkytz15
Also remember that the probability of having 10% of values on the right tail is EXACTLY the same as having 10% of values in the left tail because of symmetry. So this z value of 1.285 signifies that 10% of values lies in the lower left tail also. If your test statistic falls below this value, it basically means that the mean of the population is getting further and further down from 50 and the case for rejecting the null hypothesis is really strong. (Null hypothesis claims that population mean is greater than or equal to 50)
In our case, the test statistic doesnt fall below 1.285 and so null cannot be rejected.
Hope this helps.