Question Help Suppose you buy a new car whose advertised mileage is 20 miles per gallon​ (mpg). After driving your car for several​ months, you find that its mileage is 15.5 mpg. You telephone the manufacturer and learn that the standard deviation of gas mileages for all cars of the model you bought is 1.21 mpg. a. Find the​ z-score for the gas mileage of your​ car, assuming the advertised claim is correct. b. Does it appear that your car is getting unusually low gas​ mileage?

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Q: standard deviation is s = 30. Determine the test statistic for this test.

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Q: None

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Confidence Intervals

When we calculate intervals in probability and statistics, it can be simply termed as finding out a confidence interval. The confidence interval is usually calculated from the data set which is observed. The value of the parameter that needs to be calculated is present here only.