Weatherwise is a magazine published by the American Meteorological Society. One

Question

Weatherwise is a magazine published by the American Meteorological Society. One issue gives a rating system used to classify Nor'easter storms that frequently hit New England and can cause much damage near the ocean. A severe storm has an average peak wave height of ? = 16.4 feet for waves hitting the shore. Suppose that a Nor'easter is in progress at the severe storm class rating. Peak wave heights are usually measured from land (using binoculars) off fixed cement piers. Suppose that a reading of 37 waves showed an average wave height of x = 17.5 feet. Previous studies of severe storms indicate that ? = 3.5 feet. Does this information suggest that the storm is (perhaps temporarily) increasing above the severe rating? Use ? = 0.01.

Explanation / Answer

(a) What is the level of significance?

? = 0.01


State the null and alternate hypotheses.

H0: ? = 16.4 ft; H1: ? > 16.4 ft


(b) What sampling distribution will you use? Explain the rationale for your choice of sampling distribution.

The standard normal, since the sample size is large and ? is known.


What is the value of the sample test statistic? (Round your answer to two decimal places.)

z-statistic = (17.3 - 16.4) / (3.5 / sqrt 38) = 1.59


(c) Find the P-value. (Round your answer to four decimal places.)

P-value = P(z > 1.59) = 0.0559


(d) Based on your answers in parts (a) to (c), will you reject or fail to reject the null hypothesis? Are the data statistically significant at level ??

At the ? = 0.01 level, we fail to reject the null hypothesis and conclude the data are not statistically significant.

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