Question

What is the Z score for items 9 and 11. Are they truly abnormal?

	Data
1	223
2	200
3	154
4	217
5	223
6	157
7	178
8	159
9	350
10	243
11	325
12	298

Answer 1

from above:

Z score for items 9 =(Xbar-mean)/standard deviation =(350-227.25)/66.16=1.86

Z score for items 11 =(Xbar-mean)/standard deviation =(350-325)/66.16=0.38

as z score absolute value is not higher than 2 ; therefore these are not truly abnormal.