(Solved by Humans)-A study of pollutants showed that certain industrial measures

Question

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)

(b) Is the test one-tailed or two-tailed? Answer: _____ (answer 1 or 2)

(c) To 3 decimal places the critical value of the test statistic for this hypothesis test is: ______? (Answer in the form x.xxx or -x.xxx)

(d) To 3 decimal places the test statistic calculated from the sample is: _______(Answer in the form?x.xxx or -x.xxx)

(e) Is the null hypothesis rejected at the 5% level? Answer: ____? (Answer YES or NO)

(f)Does this mean that the pollution levels are satisfactory? ?Answer: ______(Answer YES or NO)

(g) Is it necessary to assume that air test results are normally distributed in order to apply this hypothesis test? _____? (Answer YES or NO)