6
QuizMultiple Choice

Statistical Modeling — Test

Question 6 • Statistical Reasoning

Data were collected from a typing class with 45 students. The class had an average of 56 words per minute (WPM) with a standard deviation of 7 WPM. The teacher realized that the data from one student who typed 55 WPM was not entered. If this student’s results were included in the data set, what effect would it have on the standard deviation?

Answer
A
The standard deviation would be about the same, perhaps a little larger.
B
The standard deviation would be noticeably smaller.
C
The standard deviation would be about the same, perhaps a little smaller.
D
The standard deviation would be noticeably larger.

Explanation

The missing score, 55 WPM, is only 1 WPM below the class average of 56, so it is close to the center of the data. Adding a score so close to the mean slightly reduces the spread; it would not change the standard deviation much. Therefore, it would be about the same, perhaps a little smaller.

AI-written and checked against the verified answer.

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