A science teacher gives a test with 15 questions. This teacher is a hard grader.

Question

A science teacher gives a test with 15 questions. This teacher is a hard grader.

The teacher assigns points in the following manner: 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 can we conclude given a standard deviation of -2.3?

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.

Explanation / Answer

here it is given that standard deiation is -2.3

But, standard deviation can not be a negative value. Because it is the square root of variance. Variance is always positive.

So, the correct option is Option-A) The standard deviation was calculated incorrectly.

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