A random sample is to be selected from a population that has a proportion of successes p = 0.64. Determine the mean and standard de sizes. (Round your standard deviations to four decimal places.) (a) n = 20 mean 0.64 standard deviation (b) n = 30 mean standard deviation (c) n = 40 mean standard deviation (d) n = 60 mean standard deviation (e) n = 110 mean standard deviation (f) n = 210 mean standard deviation