A commuter railroad serving certain suburban community has averaged just under 1000 fares for each day throughout workdays in the past year. It is known that this number of fares x is a value of random variable X that has probability distribution with unknown mean µ and known standard deviation σ = 50. A random sample of n = 36 workdays throughout this year indicates a sample average of = 973.6 paid fares.
1. Employ the above information to find out a 90% Confidence Interval for µ.