1. The problem statement, all variables and given/known data An independent bank, concerned about its customer base, decided to conduct a survey of bank customers. Out of 505 customers who returned the survey form, 258 rated the overall bank services as excellent. (a) Test, at level α = .10, the null hypothesis that the proportion of customers who would rate the overall bank services as excellent is .46 versus a two-sided alternative (b) Calculate the p-value and comment on the strength of evidence. 3. The attempt at a solution a) the proportion of customers in the sample who rated the service as excellent is 258/505 the null hypothesis is that μ = .46. The alternatives are that μ < .46 or μ > .46. we reject the null when Z> 1.645 or Z < -1.645 Z = (X-μ)sqrt(n)/s = (258/505 - .46)sqrt(505)/s but I am running into a problem because I don't know s so I am wondering if I did this wrong?