Concept explainers
(a)
State whether the new student’s score increases or decreases the average score.
(a)
Answer to Problem 27CE
Decrease.
Explanation of Solution
For 24 students, the average score is 74 points with a standard deviation of 8.9 points.
For one student, who took the make-up the following day, secured 64 points on the exam.
Based on the information, the new student’s score is less than the average of the 24 previous scores.
Therefore, the new score decreases the average score.
(b)
Obtain the new average.
(b)
Answer to Problem 27CE
The new average is 73.5.
Explanation of Solution
Calculation:
The new average is obtained as given below:
(c)
State whether the new student’s score increases or decreases the standard deviation of the scores.
(c)
Answer to Problem 27CE
Increase.
Explanation of Solution
Based on the given information, the standard deviation is 8.9 points.
The new mean is decreased in Part (b). In the same way, the standard deviation of the new score is more than one standard deviation away from the mean of 74.
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