Question

A test has a mean of 80 with a standard deviation of 4. Which of the following scores is within one standard deviation of the mean?
A
75
B
77
С
BO
D
90
E
09

Answer 1

Answer:

B

Step-by-step explanation:

Mathematically, we shall be using the z-score here

Z-score = (x-mean)/SD

From the question, mean = 80 and SD = 4

So we want to get the option in the question that has a z-score of 1 or below

Let’s look at 75

80-75 = 5 ( this is clearly above 1 standard deviation of 4)

For 77;

80 -77 = 3

This is less than the standard deviation of 4, meaning it is within 1 standard deviation of the mean