I'm having a hard time to complete all the calculations, I always end up having wrong answers in the practice textbook. Could you help me with these problems ?

In each of the following cases, find the mean, variance, and standard deviation of the sampling distribution of the sample proportion 19?. (a) p = .5, n = 245 (Round variance to 6 decimal places and standard deviation to 4 decimal places. Do not round intermediate values.) MID-hat) = p o(p-hat)"2 o(p-hat) (b) p = .4, n = 123 (Round variance to 6 decimal places and standard deviation to 4 decimal places. Do not round intermediate values.) (c) p= .7, n= 410 (Round variance to 6 decimal places and standard deviation to 4 decimal places. Do not round intermediate values.) H(p-hat) = p o(p-hat)^2 o(p-hat) (d) p=.91, n= 1,025 (Round variance to 6 decimal places and standard deviation to 4 decimal places. Do not round intermediate values.) H(p-hat) = p o(p-hat)12 o(p-hat)