Probability based on Binomial distribution.
The United States Postal Service report 95 percent of first class mail within the same city is delivered within two days of the time of mailing. Six letters are randomly sent to different locations.
a. What is the likelihood that all six arrive within two days?
b. What is the possibility that exactly five arrive within two days?
c. Find out the mean number of letters that will arrive in two days.
d. calculate the variance and standard deviation of the number that will arrive within two days