Answer:
Standard deviation decreases and mean increases
Step-by-step explanation:
The test scores are:
42, 72, 74, 78, 80, 80, 85, 88, 92
Mean = (42 + 72 + 74 + 78 + 80 + 80 + 85 + 88 + 92)/9 = 76.77
Median is 5th term which is 80
Range is highest score - lowest score = 92 - 42 = 50
Standard deviation from an online calculator gives 13.69
Now,we want to know what happens to those values when the outlier is removed. The outlier in this case is 42 because it is not consistent with other scores which range from 72 - 92.
Thus,the new set of scores are;
72, 74, 78, 80, 80, 85, 88, 92
New Mean = (72 + 74 + 78 + 80 + 80 + 85 + 88 + 92)/8 = 81.125
New Median will be the average of the 4th and 5th term which is (80 + 80)/2 = 80
New Range = 92 - 72 = 20
New Standard deviation from an online calculator gives 6.39
From the comparison above when the outlier is removed, we can say that;
- Mean increases
- remains the same
- Range decreases
- standard deviation decreases