The null hypothesis is that we are sampling from a population with a mean of 500 and standard deviation of 100 (*H*_{0}: * m* = 500). With *α* set at .05, we use the *p*–*z* converter, we find that the *z*-score which corresponds to a one-tailed *p*-value of .05 is 1.645. We can use this *z*-score to calculate the critical value for a sample mean for a particular sample size, in this case, 25.