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zavuch27 [327]
2 years ago
15

A science teacher gives a test with 15 questions. This teacher is a hard grader. The teacher assigns points in the following man

ner: a correct answer =+1 point, an incorrect answer =−1 point, no answer =0 points. So scores on the test could range from +15 to −15. The teacher’s assistant calculates the standard deviation for scores on the test and reports SD =−2.3. What do we know?
- The standard deviation was calculated incorrectly.
- Most students received negative scores.
- Most students scored below the mean.
- There is an outlier that has a negative value close to -15.
Mathematics
1 answer:
ASHA 777 [7]2 years ago
6 0

Answer:  The standard deviation was calculated incorrectly.

Step-by-step explanation:

  • The standard deviation measures the dispersion of the data values from the mean value.

It cannot be negative , because it is the square root of the variance .

We add all squared deviations from the data points away from the mean and (then divide it by the number of data values) to evaluate variance.

Since , any squared number cannot give a negative result.

⇒ Standard deviation cannot be negative.

⇒The standard deviation was calculated incorrectly.

Rest other things (given in options) can not be interpreted on the basis of given information.

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