Question

which scores, if any, would be considered unusual?
○ a. 0
○ b. 1.42
○ c. −2.11
○ d. none

Explanation:

Step1: Recall the rule for unusual z - scores

In statistics, a z - score is considered unusual if \(|z|>2\) (some sources use \(|z| > 2.5\) or \(|z|>3\), but the common threshold for a basic understanding is \(|z|>2\)).

Step2: Check each option

• For option A: The z - score is \(0\). The absolute value \(|0| = 0\), and \(0<2\), so it is not unusual.
• For option B: The z - score is \(1.42\). The absolute value \(|1.42|=1.42\), and \(1.42 < 2\), so it is not unusual.
• For option C: The z - score is \(- 2.11\). The absolute value \(|-2.11| = 2.11\), and \(2.11>2\), so it is unusual.

Answer:

C. \(-2.11\)