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
