Int. J. Production Economics 67 (2000) 201
Letter to the Editor
Observation on:
&&
Economic production quantity model
for items with imperfect quality
''
[Int. J. Production Economics
64 (2000) 59
}
64]
Leopoldo Eduardo Ca
H
rdenas-Barro
H
n
Department of Industrial Engineering Instituto Tecnolo&gico y de Estudios Superiores de Monterrey, ITESM, Campus Monterrey, Me&xico, E. Garza Sada 2501 Sur, C.P. 64 849, Monterrey, N.L. Mexico
Salameh and Jaber presented the above-mentioned paper, which contains an error in Eq. (10) on p. 62.
This equation was used in a numerical example and the error only a!ects the optimum value of the order size.
The objective of this note is to present the correct equation and numerical results.
In Eq. (10) a constant parameter is missing; the denominator of it contains the expression
D(1!E[1/(1!p)])/x, which must be multiplied by the number`2a. Eq. (10) should be read as
yH"
S
2KDE[1/(1 !p)]h[1!E[p]!(2)(D/x)(1!E[1/(1!p)]]. (10)
And the"nal numerical result for the example must be
yH"
S
(2)(100)(50000)(1.02055)5[1!0.02!(2)(50000/175200)(1!1.02055)],
y*"1434.6156+1435units.
Substitutingy*"1435 units in Eq. (8) the maximum pro"t per year is given as
ETPU(1435)"(50000)
C
50!20#(5)(1435)175200
D
#(50000)C
20!(5)(1435)
175200!25!0.5!
100
1435
D
!(5)(1435)(1
!0.02)
2 ,
ETPU(1435)"1,212,235/year. (8)
Finally, the error does not a!ect the main idea and the remainder of the article.
