A random sample is to be selected from a population that has a proportion of successes p = 0.25. Determine the mean and standard deviation of the sampling distribution of p for each of the following sample sizes. (Round your standard deviations to four decimal places.) (a) n = 10 mean standard deviation (b) n = 20 mean standard deviation (c) n = 30 mean standard deviation (d) n = 50 mean standard deviation (e) n = 100 mean standard deviation (f) n = 200 mean standard deviation