A normal distributed population has parameters μ=15.5μ=15.5 and σ=81σ=81. If a random sample of size n=205n=205 is selected, What is the mean of the distribution of sample means? μ¯x=μx¯=  What is the standard deviation of the distribution of sample means? Round to two decimal places. σ¯x=σx¯=

A population of values has a normal distribution with μ=216.7μ=216.7 and σ=12.4σ=12.4. You intend to draw a random sample of size n=186n=186.What is the mean of the distribution of sample means?μ¯x=μx¯= What is the standard deviation of the distribution of sample means?(Report answer accurate to 2 decimal places.)σ¯x=σx¯=

A population has mean u=30 and standard deviation o=7. (A) Find the z-score for a population value of 9. (B) Find the z-score for a population value of 51. (C) What number has a z-score of -2.3

To compare the dry braking distances from 30 to 0 miles per hour for two makes of​ automobiles, a safety engineer conducts braking tests for 35 models of Make A and 35 models of Make B. The mean braking distance for Make A is 43 feet. Assume the population standard deviation is 4.6 feet. The mean braking distance for Make B is 46 feet. Assume the population standard deviation is 4.5 feet. At α=0.10​, can the engineer support the claim that the mean braking distances are different for the two makes of​ automobiles? Assume the samples are random and​ independent, and the populations are normally distributed.   The critical​ value(s) is/are   Find the standardized test statistic z for μ1−μ2.