1.The average length of a flight by regional airlines in the United States has been reported as 464 miles. If a simple random sample of 30 flights by regional airlines were to havex 479.6 miles and s...

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Extracted text: 1.The average length of a flight by regional airlines in the United States has been reported as 464 miles. If a simple random sample of 30 flights by regional airlines were to havex 479.6 miles and s = 42.8 miles, would this tend to cast doubt on the reported average of 464 miles? Use a two-tail test and the 0.05 level of significance in arriving at your answer. 2. A scrap metal dealer claims that the mean of his cash sales is “no more than $80," but an Internal Revenue Service agent believes the dealer is untruthful. Observing a sample of 20 cash customers, the agent finds the mean purchase to be $91, with a standard deviation of $21. Assuming the population is approximately normally distributed, and using the 0.05 level of significance, is the agent's suspicion confirmed? 3. A factory has a machine that dispenses 80ml of fluid in a bottle. An employee believes the average amount of fluid is not 80ml. Using 40 samples, he measures the average amount dispensed by the machine to be 78ml with a standard deviation of 2.5. At a significance level of 95%, is there enough evidence to support the idea that the machine is working properly?