When testing gas pumps for accuracy, fuel-quality enforcement specialists tested pumps and found that 1304 of them were not pumping accurately (within 3.3 oz when 5 gal is pumped), and 5689 pumps were accurate. Use a 0.01 significance level to test the claim of an industry representative that less than 20% of the pumps are inaccurate.
6) When testing gas pumps for accuracy, fuel-quality enforcement specialists tested pumps and found that 1304 of them were not pumping accurately (within 3.3 oz when 5 gal is pumped), and 5689 pumps were accurate. Use a 0.01 significance level to test the claim of an industry
representative that less than 20% of the pumps are inaccurate.
7) A coin mint has a specification that a particular coin has a mean weight of 2.5 g. A sample of 39 coins was collected. Those coins have a mean weight of 2.49428 g and a standard deviation of 0.01367 g. Use a 0.05 significance level to test the claim that this sample is from
a population with a mean weight equal to 2.5 g. Do the coins appear to conform to the specifications of the coin mint?
8) Suppose a mutual fund qualifies as having moderate risk if the standard deviation of its monthly rate of return is less than 6%. A mutual-fund rating agency randomly selects 26 months and determines the rate of return for a certain fund. The standard deviation of the rate of return is computed to be 5.47%. Is there sufficient evidence to conclude that the fund has moderate risk at the α=0.01 level of significance? A normal probability plot indicates that the monthly rates of return are
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