Customers can replace 1, 2, 3, or 4 tires at a time for their vehicle at Tire Masters, a nationwide tire shop chain. For customers who have had their tires replaced at Tire Masters, the mean number of tires replaced is u= 2.75, with a standard deviation of o = 0.65. Suppose that we will take a random sample of n=8 tire replacement orders. (Each order gives the number of tires being replaced.) Let x represent the sample mean of the 8 tire replacement orders. Consider the sampling distribution of the sample mean x. Complete the following. Do not round any intermediate computations. Write your answers with two decimal places, rounding if needed. (a) Find (the mean of the sampling distribution of the sample mean). (b) Find o- (the standard deviation of the sampling distribution of the sample mean).

A standardized exam's scores are normally distributed. In a recent year, the mean test score was 1539 and the standard deviation was 315. The test scores of four students selected at random are 1940, 1290, 2240, and 1420. Find the z-scores that correspond to each value and determine whether any of the values are unusual. The z-score for 1940 is. (Round to two decimal places as needed.) The Z-score for 1290 is. (Round to two decimal places as needed.) The Z-score for 2240 is. (Round to two decimal places as needed.) The Z-score for 1420 is. (Round to two decimal places as needed.) Which values, if any, are unusual? Select the correct choice below and, if necessary, fill in the answer box within your choice. OA. The unusual value(s) is/are. CD (Use a comma to separate answers as needed.) OB. None of the values are unusual.

A standardized exam's scores are normally distributed. In a recent year, the mean test score was 1458 and the standard deviation was 312. The test scores of four students selected at random are 1860, 1220, 2150, and 1340. Find the z-scores that correspond to each value and determine whether any of the values are unusual. The z-score for 1860 is (Round to two decimal plaes as needed.)

Assume that the readings at freezing on a batch of thermometers are normally distributed with a mean of 0°C and a standard deviation of 1.00°C. A single thermometer is randomly selected and tested. Find P87, the 87-percentile. This is the temperature reading separating the bottom 87% from the top 13%.P87 = °C

If we meet these conditions, the sampling distribution of the mean will have a normal shape and ... The mean of the sampling distribution will be u, (i.e., the same as the population mean) and the standard deviation of the sampling distribution will be (that's the population standard deviation divided by the square root of the sample size). In the AP Stats Guy video, he talks about the number of text messages his students send during class. Suppose the average number of text messages his students send during class is u = 30 text messages. If we take samples of say, n = 36 students at a time, we would expect the mean of the sampling distribution we create to be the same as the population mean, 30 text messages. If we can further say that standard deviation of the number of text messages is 12 text messages, by how much would we expect the sample means to vary? (hint, use the formula above) text messages

A standardized exam's scores are normally distributed. In a recent year, the mean test score was 1506 and the standard deviation was 317. The test scores of four students selected at random are 1940, 1230, 2190, and 1400. Find the z-scores that correspond to each value and determine whether any of the values are unusual. The z-score for 1940 is. (Round to two decimal places as needed.)