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The speed limit monitoring device on West Street is used to inform drivers how fast they are going. I watch it and find that the mean from a random sample of 40 cars is 31.1 miles per hour (mph) with a standard deviation of 6.2 mph. Use a 0.05 significance level to test the claim that the mean speed of all drivers on West Street is more than 5 mph above the posted speed limit of 25 mph. 18) Salmon: Assume that the weights of spawning Chinook Salmon in the Columbia River are normally distributed. You randomly catch and weigh 20 such salmon. The mean weight from your sample is 25.2 pounds with a standard deviation of 4.5 pounds. (a) Test the claim that the mean weight of Columbia River salmon is greater than 23 pounds. Use a 0.10 significance level. 2) Sleep: Suppose you perform a study about the hours of sleep that college students get. You know that for all people, the average is about 7 hours. You randomly select 50 college students and survey them on their sleep habits. From this sample, the mean number of hours of sleep is found to be 6.2 hours with a standard deviation of 0.75 hours. In the previous chapter we calculated a 99% confidence interval for the mean number of hours of sleep to college students as 5.9