A report states that the average age of commercial airliners in the United States is 11 years with a standard deviation of 2.7 years. A researcher wants to test this claim and finds that a random sample of 40 planes from around the United States has an average age of 12.5 years. At an

= 0.05,

can you conclude that the average age of airliners has increased?(a)What is the test statistic for this scenario?

Find the critical value(s) that correspond to the following situations. Assume we know, so we can use the standard normal distribution. (Usea tableor technology. Round your answers to two decimal places.)(a)an upper-tailed test with =0.1 (b)a two-tailed test with =0.02?

It is claimed that the heights of young men at a large university are approximately normally distributed, with a mean of69.6inches.A random sample of heights from the university are listed below (in inches).

72

65

72

77

69

75

69

69

72

71

70

These data were used to calculate the following sample mean and standard deviation.

n= 11 x=71 s=3.2249

Is there sufficient evidence to say that the mean height of men at the university is taller than the claimed69.6inches?(a)Assume the conditions are met to perform attest. Calculate the test statistic. (Round your answer to three decimal places.)

t= (b)What is the critical value associated with a one-tailed test when

= 0.1?

(Usea tableor technology. Round your answer to three decimal places.)

(c)Choose the appropriate conclusion for this test.

Accept the null hypothesis. Reject the alternative hypothesis. Fail to reject the null hypothesis. Reject the null hypothesis.