Page 65 - Contributed Paper Session (CPS) - Volume 2

CPS1428 Enobong F. U.
of the areas corresponding to the Pearson Type I, IV, and VI on the skewness-
Kurtosis plane. Some sections of normal, exponential, logistic, extreme value
and lognormal distributions are also covered. Burr XII accommodates a
positive longer tail probability than the PERT-beta distribution. Lewis (1981)
further presented the Weibull, Exponential, Generalized Logistic, Logistic,
Normal, Pareto, and Gompertz distributions as special cases of Burr XII
distribution.

3. Illustration and Discussions
In a study of water bore hole drilling projects in Makurdi, North Central
region of Nigeria by Nile Drill Tech, limited, a total of 20 drilling sites were
observed. The project was divided into 9 activities.
A description of the activities in the project is given in table 1.

Table1: Activity Description with Duration times (in minutes)
Activity Description Mean Median Mode Variance Skewness Min Max
A Geographical 32.95 31 30 22.3658 1.4976 28 45
Survey
B Analysis of 63.1 61 60 34.7263 1.7203 56 80
data
C Punching 315.55 305.5 300 811.8394 0.9950 280 380
D Casing 30.75 30 30 3.25 1.1940 28 35
E Gravel 16.55 16 15 6.7868 1.6038 14 24
Packing
F Connection
of pipes to
pump 202.25 185 180 1782.8289 1.3595 150 300
G Connection
of cables to
pump 23.95 24 25 7.8395 1.0320 20 32
H Lowering of 3 3 3 0.6316 0.6991 2 5
pump
I Plumbing 103.7 100 100 113.8 1.0126 90 130

In table 2 we present the estimates of the mean duration of activities A-I
using quantile estimation method (new method). traditional PERT, Gollenko-
Ginzburg method, and Shankar approximation, and simulated results. From
table 2, it could be observed that the mean estimates obtained using the new
method are generally higher than those obtained using the three previous
methods with exception of activity H. However we note from table I that
activity H has almost symmetric distribution with coefficient of skewness =
0.6991.

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