Assume a binomial probability distribution with n = 40 and p = .55. Compute the following:
a. The mean and standard deviation of the random variable. (Round your answer to 2 decimal places.)
Mean 22 Standard deviation 3.15
b. The probability that X is 25 or greater. (Round your answer to 4 decimal places.)
Probability 0.1711
c. The probability that X is 15 or less. (Round your answer to 4 decimal places.)
Probability 0.0132
d. The probability that X is between 15 and 25 inclusive. (Round your answer to 4 decimal places.)
Probability 0.8157
The mean and standard deviation is right according to the answer check, but somehow when i use the number to calculate the rest of b,c,d; all of them are wrong in the end. Please explain as much details as possible.