Independent random samples of vehicles traveling past a given point on an interstate highway have been observed on Monday versus Wednesday. For 16 cars observed on Monday, the average speed was 59.4 mph, with a standard deviation of 3.7 mph. For 20 cars observed on Wednesday, the average speed was 56.3 mph, with a standard deviation of 4.4 mph. At the 0.05 level, and assuming normal populations, what is the calculated value of test statistic, t? (Specify your answer to the 3rd decimal.)