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# Sample size for the estimation of mean

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A consumer agency has retained an independet testing firm to examine a television manufacturer's claim that its 25-inch console lmodel consumes just 110 watts of electricity. Based on a preliminary study, the population standard deviation has been estimated as 11.2 watts for these sets. In undertaking a larger study, and using a simple random sample, how many sets must be tested for the firm to be 95% confident that its sample mean does not differ from the actual population mean by more than 3.0 watts?

2. For each of the following pairs of null and alternative hypotheses, determine whether the pair would be appropriate for a hypothesis test. If a pair is deemed inappropriate explain why?
a. Ho:II>0.30, H1:II<0.35
b. Ho:II= 0.72 H1:II=0.72
c. HO:II < 0.25 H1: II > 0.25
d. Ho: II > 0.48 H1: II > 0.48
e. Ho: II < 0.70 h1: II > 0.70
f. Ho:p > 0.65 H1:p < 0.65