an automobile manufacturer has given its car a 59.5 miles/gallon (mpg) rating. an independent testing firm has been contracted to test the actual mpg for this car since it is believed that the car performs over the manufacturer's mpg rating. after testing 250 cars, they found a mean mpg of 59.6. assume the population standard deviation is known to be 1.9. is there sufficient evidence at the 0.05 level to support the testing firm's claim? step 2 of 6 : find the value of the test statistic. round your answer to two decimal places.