1. Construct the indicated confidence intervals for the population variance : c=0.99, S2 = 0.64, n=7

2. An auto manufacturer believes that the variance of the gas mileages of its hybrid vehicles is 1.0. You work for an energy conservation agency and want to test this claim. You find that a random sample of the gas mileages of 25 of the manufacturers hybrid vehicles has a variance of 1 65. At a=0.05, do you have enough evidence to reject the manufacturer's claim?

3. Test the claim μ₂ > μ₁. α = 0.1 Sample statistics: x₁ = 5.2, s₁ - 0.2, n₁ = 45 and x₂ = 5.5, s₂ = 0.3, n₂ = 37

4. A personal director from Florida claims that the mean household income is greater in Hillsborough County than it is on Polk County. In Hillsborough County, a sample of 10 residents had a mean household income of $49,800 and a standard deviation of $4,200. In Polk County, a sample of 16 residents has a mean household income of $44,400 and a standard deviation of $8,600. At a=0.1, can you support the personnel director's claim? Assume the population variances are equal.