Each student number is nine digits long. Treat each digit in your student number as if it were taken individually from a population with a mean of 4 and an unknown population standard deviation. For example, if your student number is 123456789, that means the digits

1,2,3,4,5,6,7,8,9

1,2,3,4,5,6,7,8,9

were randomly generated one at a time from the population.

a) Do a 95% confidence interval for the digits of your student number.

b) With 95% confidence, use a hypothesis test to determine if the digits of your student number were taken from a population with a mean of 4 and an unknown population standard deviation.