Broadtred Tire Co.
Enter data only in the shaded cells
This spreadsheet is designed to calculate the probability of values equal to, or less than, a desired x value,
given the mean and standard deviation of a normally distributed variable. It uses the cumulative normal distribution
Enter the mean of the distribution in shaded cell D8 and the standard deviation in shaded cell D9. below.
Enter the desired X-value in shaded cell D10, below. The calculated z-value and probability will be seen in D11 and D12.
Part a Part b Part d
Mean of distribution 50000 50000 z = -1.2816 NORMAL PROBABILITY CALCULATIONS
Std deviation of distribution 2500 2500
Calculated z-value 1.20
(X-axis) Probability Using Prob. of x, or less 0.88493
Desired x-values
Equivalent – Z Values
NORM.DIST
40000 -4.00 0.00003 Equivalent Probability Using Desired
40250 -3.90 0.00005 Z Values NORM.DIST x-values
40500 -3.80 0.00007 -4.00 0.00003 940
40750 -3.70 0.00011 -3.60 0.00016 948
41000 -3.60 0.00016 -3.20 0.00069 956
41250 -3.50 0.00023 -2.80 0.00256 964
41500 -3.40 0.00034 -2.40 0.00820 972
41750 -3.30 0.00048 -2.00 0.02275 980
42000 -3.20 0.00069 -1.60 0.05480 988
42250 -3.10 0.00097 -1.20 0.11507 996
42500 -3.00 0.00135 -0.80 0.21186 1004
46000 -1.60 0.05480
46250 -1.50 0.06681
46500 -1.40 0.08076
46750 -1.30 0.09680
47000 -1.20 0.11507
47250 -1.10 0.13567
47500 -1.00 0.15866
47750 -0.90 0.18406
48000 -0.80 0.21186
48250 -0.70 0.24196
48500 -0.60 0.27425
48750 -0.50 0.30854
49000 -0.40 0.34458
49250 -0.30 0.38209
49500 -0.20 0.42074
49750 -0.10 0.46017
50000 0.00 0.50000
50250 0.10 0.53983
56000 2.40 0.99180 <– x = 56000
56250 2.50 0.99379
56500 2.60 0.99534
56750 2.70 0.99653
57000 2.80 0.99744
57250 2.90 0.99813
57500 3.00 0.99865
57750 3.10 0.99903
58000 3.20 0.99931
58250 3.30 0.99952
58500 3.40 0.99966
58750 3.50 0.99977
59000 3.60 0.99984
59250 3.70 0.99989
59500 3.80 0.99993
59750 3.90 0.99995
60000 4.00 0.99997
0.40
0.50
0.60
0.70
0.80
0.90
1.00
Cumulative Probability Function
Calculated z-value 1.20
Prob. of x, or less 0.88493
Equivalent Probability Using Desired
Z Values NORM.DIST x-values
-4.00 0.00003 940
-3.60 0.00016 948
-3.20 0.00069 956
-2.80 0.00256 964
-2.40 0.00820 972
-2.00 0.02275 980
-1.60 0.05480 988
-1.20 0.11507 996
-0.80 0.21186 1004
Mean of distribution 1020
Std Dev of distribution 20
Desired x-value 1044