Data Set 8-4 :A random sample of 64 students produced the following statistics: = 18.00, = 7.00.
-For Data Set 8-4 the probability of obtaining such a sample mean (or one smaller) from a population with a mean of 20 and a standard deviation of 8 is
A) .4772
B) .4013
C) .0987
D) 0.0228

Question

Quizplus · Accepted Answer

The sample mean is 18, the population mean is 20, and the standard deviation is 8. The sample size is 64. Using the standard error formula (population standard deviation divided by the square root of the sample size), we calculate the standard error as 8/√64 = 1. The z-score is (18-20)/1 = -2. The probability of obtaining a z-score of -2 or smaller is 0.0228.

Data Set 8-4 :A Random Sample of 64 Students Produced