Enter α:

Given α = 0.9

Calculate the right-tailed and left-tailed critical value for Z

Calculate right-tailed value:

Since α = 0.9, the area under the curve is 1 - α → 1 - 0.9 = 0.1

Our critical z value is

Excel or Google Sheets formula:

Excel or Google Sheets formula:=NORMSINV(0.1)

Calculate left-tailed value:

Our critical z-value =

Excel or Google Sheets formula:

Excel or Google Sheets formula:=NORMSINV(0.9)

Critical Z value table:

zProbability (Area under Curve)
-2.32630.01
-2.05370.02
-1.88080.03
-1.75070.04
-1.64490.05
-1.55480.06
-1.47580.07
-1.40510.08
-1.34080.09
-1.28160.10
-1.22650.11
-1.1750.12
-1.12640.13
-1.08030.14
-1.03640.15
-0.99450.16
-0.95420.17
-0.91540.18
-0.87790.19
-0.84160.20
-0.80640.21
-0.77220.22
-0.73880.23
-0.70630.24
-0.67450.25
-0.64330.26
-0.61280.27
-0.58280.28
-0.55340.29
-0.52440.30
-0.49590.31
-0.46770.32
-0.43990.33
-0.41250.34
-0.38530.35
-0.35850.36
-0.33190.37
-0.30550.38
-0.27930.39
-0.25330.40
-0.22750.41
-0.20190.42
-0.17640.43
-0.1510.44
-0.12570.45
-0.10040.46
-0.07530.47
-0.05020.48
-0.02510.49
00.50
0.02510.51
0.05020.52
0.07530.53
0.10040.54
0.12570.55
0.1510.56
0.17640.57
0.20190.58
0.22750.59
0.25330.60
0.27930.61
0.30550.62
0.33190.63
0.35850.64
0.38530.65
0.41250.66
0.43990.67
0.46770.68
0.49590.69
0.52440.70
0.55340.71
0.58280.72
0.61280.73
0.64330.74
0.67450.75
0.70630.76
0.73880.77
0.77220.78
0.80640.79
0.84160.80
0.87790.81
0.91540.82
0.95420.83
0.99450.84
1.03640.85
1.08030.86
1.12640.87
1.1750.88
1.22650.89
1.28160.90
1.34080.91
1.40510.92
1.47580.93
1.55480.94
1.64490.95
1.75070.96
1.88080.97
1.960.975
-1.960.025
2.05370.98
2.32630.99
-2.57580.005
2.57580.995

Final Answer


Right tail value =
Left tail value =


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How does the Critical Z-values Calculator work?
Free Critical Z-values Calculator - Given a probability from a normal distribution, this will generate the z-score critical value. Uses the NORMSINV Excel function.
This calculator has 1 input.
What 1 formula is used for the Critical Z-values Calculator?
Z = (x - μ)/σ/√n
What 3 concepts are covered in the Critical Z-values Calculator?
area
Number of square units covering the shape
critical value
a point on the distribution of the test statistic under the null hypothesis that defines a set of values that call for rejecting the null hypothesis.
critical z-values
Example calculations for the Critical Z-values Calculator
Critical Z-values Calculator Video

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