Calculate M using the data Exercise 6.78. Data from exercise 6.78 A Veterans Administration researcher has

Calculate σ_M using the data Exercise 6.78.

Data from exercise 6.78

A Veterans Administration researcher has developed a test that is meant to predict combat soldiers’ vulnerability to developing posttraumatic stress disorder (PTSD). She has developed the test so that μ = 45 and σ = 15. She is curious if victims of violent crime are as much at risk for PTSD as combat veterans. So, she obtains a sample of 122 recent victims of violent crime and administers the test to each one of them. She’s planning to use a single sample z test, two-tailed and with alpha set at .05, to compare the sample mean (42.8) to the population mean. Check the assumptions and decide if it is OK to proceed with the single sample z test.