Data Reduction
23
The infinite sample size Weibull parameters for 95% confidence from the 755
test sample using Eq. (1.37)
I--0.78 Z~/2l
1-+0.78 z~/=l
BexPL- Tj
Tj J
from Table 1.1
Z~/2 = 1.960 N = 755
0.945881 B substituting B from Eq. (1.77) the infinite sample size
4.34283 while the computer yields on 755 samples
4.24996 (1.81)
then from Eq. (1.38)
0 exp ~--~/~ -j <_ 0 _< 0 exp ~-~ -j
using
with
then
B = 4.59132 Eq. (1.77)
N = 7.55
0.9838190 < O < 1.016450
0 = 33.850 Eq. (1.77)
Za/2 ~-~ 1.960
33.3032 < O < 34.4077
(1.82)
with from the computer for 755 samples
31.6164 _< O _< 36.0853
now the lower value of y is evaluated using KA values from Eq. (1.78)
~AL = X -- KAS
7aL = 145.707 Ksi - 2.45 (2.153)
TAL -= 140.432 Ksi
140.432 Ksi < 7A < 150.984 Ksi
Also
136.123 < y¢ < 155.291 Ksi
while the computer for 755 samples
143.554 <_ ~ < 147.860 Ksi
(1.83)