A telephone company has reason to believe that the proportion of households having three telephone numbers is less than 30%. A marketing survey of 175 households gives the result that 42 of the households have three telephone numbers. Test at a 5% significance level the telephone company's claim. State the hypotheses:
A telephone company has reason to believe that the proportion of households having three telephone numbers is less than 30%. A marketing survey of 175 households gives the result that 42 of the households have three telephone numbers. Test at a 5% significance level the telephone company's claim. State the hypotheses:
Given eight sample observations from a normal population: 31; 29; 26; 33; 40; 28; 30; 25 so that the mean and standard deviation is respectively 30.3 and 4.7. Test the hypothesis that the sample mean differs from the population mean of 35. The rejection region at 5% significance level (rounded off to three decimal) is:
An office manager claims that the mean time required to handle a customer complaint is less than 30 minutes. A sample of 38 complaints shows a mean of 28.7 minutes and standard deviation of 12 minutes. Test the office manager's claim at a 10% significance level. The test statistic (rounded off to two decimals) is:
A stereo manufacturer claims his top-of-the-line turntable has an average lifespan of more than 15 years. When asked to provide evidence that supports this claim, he obtains from his files the names of 15 customers who have purchased this high quality turntable and asks each how long their turntables ran before needing replacement. From these 15 measurements he computes and average lifespan of 17 years with a variance of 4 years. The test statistic is 3.8730 and the critical value is 1.761, is. State your conclusion.
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