A county is considering raising the speed limit on a road because they claim that the mean speed of vehicles is greater than 40 mi/hr. A random sample of 15 vehicles has a mean speed of 43 mil/hr and a standard deviation of 4.4 mi/hr.   Assume that speeds follow a normal distribution. What statistical test should be used to test the claim?

Brewed decaffeinated coffee contains some caffeine. We want to estimațe the amount of caffeine in 8 ounce cups of decaf coffee at local fast food restaurants. For this question, assume that the standard deviation in the amount of caffeine in 8 ounces of decaf coffee is not known and is estimated to be 2.3 mg using the samplestandard deviation. This time we took a sample of n = 9 eight-ounce cups of coffee from fast food restaurants on Robert Street in West St. Paul. The sample mean amount of caffeine turned out to be 9 mg. Construct a 99% confidence interval estimate for the true mean amount of caffeine in eight-ounce cups of decaf coffee, using the new information described above. Type the formula for your confidence interval into the text box first and then type a second version where you fill in all of the numbers in your formula. You don't have to calculate the final numeric result.

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Consider a value to be significantly low if its z score less than or equal to minus2 or consider a value to be significantly high if its z score is greater than or equal to 2.A data set lists weights​ (grams) of a type of coin. Those weights have a mean of 5.42245 g and a standard deviation of 0.05893 g. Identify the weights that are significantly low or significantly high.What weights are significantly​ low? Select the correct answer below and fill in the answer​ box(es) to complete your choice.     A. Weights that are between nothing and nothing. ​(Round to five decimal places as needed. Use ascending​ order.)   B. Weights that are greater than nothing. ​(Round to five decimal places as​ needed.)   C. Weights that are less than