Each student number at York 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 were randomly generated one at a time from the population. a) make 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.