−2
−1
1
−3
3
2
0.5%
0.1%
−1.5
−0.5
1.5
−2.5
0.5
2.5
9.2%
4.4%
1.7%
9.2%
4.4%
1.7%
0.5%
0.1%
0
2.3%
15.9%
84.1%
0.1%
99.9%
97.7%
50%
1%
5%
10%
20
30
40
50
60
70
80
90%
95%
99%
−4
−3.5
4
3.5
Cumulative
Z-Score
−2σ
−1σ
+1σ
−3σ
+3σ
+2σ
0
−4σ
+4σ
Standard
Standard Normal
"Bell Curve"
Distribution
Deviation
Percent
19.1%
15.0%
15.0%
19.1%