Question

Keep cool: Following are prices, in dollars, of a random sample of ten 7.5-cubic-foot refrigerators. A consumer organization reports that the mean price of 7.5-cubic-foot refrigerators is less than $380. Do the data provide convincing evidence of this claim? Use the =α0.10 level of significance and the critical value method with the Critical Values for the Student's t Distribution Table.

344	411	359	316	349
309	366	382	327	337

Following is a dotplot for these data. Is it reasonable to assume that the conditions for performing a hypothesis test are satisfied? Explain.

The dotplot shows that there ▼are outliers. The dotplot shows that there ▼is no evidence of strong skewness. We ▼cannot assume that the population is approximately normal. It ▼is reasonable to assume that the conditions are satisfied.

Answer 1

Following is the output of dot plot:

Dot plot shows that there is no outlier. Data is almost symmetric.

It is reasonable to assume that the conditions are satisfied.

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Following table shows the calculations for mean and SD of data set:

	X	(X-mean)^2
	344	36
	411	3721
	359	81
	316	1156
	349	1
	309	1681
	366	256
	382	1024
	327	529
	337	169
Total	3500	8654

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Conclusion: There is evidence to support the claim that the mean price of 7.5-cubic-foot refrigerators is less than $380.