A study of pollutants showed that certain industrial measures should not on average exceed 2.5 parts per million. It has been claimed that a particular company may be exceeding this level. To test the claim, a random sample of 15 air tests is taken. The sample has a mean of 3.07 parts per million. Assume that the population standard deviation for this kind of test is known to be 1 part per million. The testers need to perform a hypothesis test to decide whether the sample provides sufficient evidence that the prescribed upper limit of 2.5 parts per million is in fact being violated.The test must be performed at the 5% level of significance.
(a) According to the null hypothesis, the value of the population mean is parts per million. (Answer in the form of a number with two decimal places x.xx)