Fran is training for her first marathon, and she wants to know if there is a significant difference between the mean number of miles run each week by group runners and individual runners who are training for marathons. She interviews 49 randomly selected people who train in groups, and finds that they run a mean of 47.6 miles per week. Assume that the population standard deviation for group runners is known to be 2.3 miles per week. Step 2 of 3 : Compute the value of the test statistic. Round your answer to two decimal places.