DSC04857

456

Chapter 6: Introduction to

(a)

Assuming that cr = 30 for the population of older students, cany«a_a test of

H₀: ix = 115 H_a: /x > 115

Report the P-value of your test, and State your conclusion cleariy.

(b) Your test in (a) required two important assumptions in addition to the assumption that the value of cr is known. What are they? Whiehoł these assumptions is most important to the validity of your concfaśori in (a)?

6.46 The mean yield of corn in the United States is about 120 busheis WĘm acre. A survey of 40 farmers this year gives a sample mean yield ofi -123.8 busheis per acre. We want to know whether this is good eińdence thai the national mean this year is not 120 busheis per acre. Assume that the farmers surveyed are an SRS from the population of all commercial córo growers and that the standard deviation of the yield in this populatkasis cr = 10 busheis per acre. Give the P-value for the test of

H₀: ix = 120

H_a: ix ¥> 120

Are you convinced that the population mean is not 120 busheis per aa*? Is your conclusion correct if the distribution of corn yields is soraewlNt nonnormal? Why?

6.47

In the past, the mean score of the seniors at South High on the American

_____ m__u___a_.__ . .    ___-