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 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.

Explanation / Answer

Answer is (A) , standard deviation was calculated incorrectly as the standard deviation cannot be negative because the square root of the variance is SD. Variance is always positive.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.