The Iowa department of transportation repaired hundreds of
bridges in 1993. To check the average cost to repair a bridge, a
random sample of n=55 bridges was chosen. The mean and standard
deviation for the sample are $25788 and $1540, respectively.
Records from previous years indicate an average bridge repair cost
was $25003. Use the sample data to test that the mean mu is
greater than $25003 at the level of significance alpha = 0.05.
Let T_{obs} denote the observed value of the appropriate test
statistics for this problem.