A group of 200 students takes the Kaplan course in hopes that it will improve their SAT scores above the national mean of 500 on the math section.The population standard deviation of the SAT is known to be 100.Use an alpha level of .05 when answering the following questions.The students who took the Kaplan course obtain a mean of 520 on the math SAT.Compute the one-sample z test statistic.
A)z = 2.83
B)z = 1.41
C)z = .014
D)z = .20

Question

Quizplus · Accepted Answer

We can use the formula 
z = (x - μ) / (σ / sqrt(n)) 
where x is the sample mean, μ is the population mean, σ is the population standard deviation, and n is the sample size.
Plugging in the values, we get 
z = (520 - 500) / (100 / sqrt(200)) 
z = 20 / (100 / 14.14) 
z = 20 / 7.07 
z = 2.83 
Thus, the one-sample z test statistic is 2.83.

A Group of 200 Students Takes the Kaplan Course in Hopes