Find the z-score corresponding to the given value and use the z-score to determine whether the value is unusual.
Consider a score to be unusual if its z-score is less than -2.00 or greater than 2.00. Round the z-score to the nearest tenth
if necessary.
-A weight of 224 pounds among a population having a mean weight of 158 pounds and a standard deviation of 23.5 pounds.
A) 65.8; unusual
B) 2.8; unusual
C) -2.8; not unusual
D) 2.8; not unusual

Question

Quizplus · Accepted Answer

The z-score can be calculated using the formula z = (x - μ) / σ, where x is the given value, μ is the mean, and σ is the standard deviation. 
z = (224 - 158) / 23.5 = 2.8
Since the z-score is greater than 2.00, the value is considered unusual. Therefore, the answer is choice B.

Find the Z-Score Corresponding to the Given Value and Use