Nahmias Chapter 2 Essays

1522 Words Mar 25th, 2013 7 Pages
Production and Operations Analysis, Fourth Edition

Solutions To Problems From Chapter 2 2.12 a) and b)

Forecast (86 + 75)/2 (75 + 72)/2 etc = = 80.5 73.5 77.5 107.5 98.5 87.5 100.0 78.5 79.5 95.0 = =

Period 3 4 5 6 7 8 9 10 11 12 21.6 717.5

Actual 72 83 132 65 110 90 67 92 98 73

et +8.5 -9.5 -54.5 42.5 -11.5 -2.5 +33.0 -13.5 -18.5 +22.0

c)

MAD MSE

= =

(216)/10 (7175)/10

MAPE

=

100

1  n

 ∑D i ei 

= 25.61

2.13

Fcst 1 Fcst 2 223 289 430 134 190 550 210 320 390 112 150 490

Demand 256 340 375 110 225 525

Err 1 33 51 -55 -24 35 -25

Err 2 46 20 -15 -2 75 35

Er1^2

Er2^2

|Err1| 33 51 55 24 35 25 37.16666 (MAD1)

1089 2116 2601 400 3025 225 576 4 1225 5625 625 1225 1523.5 1599.166 (MSE1 (MSE2)

Err2
46 20 15 2 75 35
…show more content…
b) c)
US Births (in 1,000,000) (Xi) 2.9 3.4 3.5 3.1 3.8 2.8 4.2 3.7 Forecasted Births Using ES(.15)

Y10 = -5.8 + (4.158)(3.3) = 7.9214 (that is, $792,140)

Hence, forecasted births for years 9 and 10 is 3.4 million.

Year 1 2 3 4 5 6 7 8 9 10

3.2 3.3 3.2 3.4 3.4 3.4

20

Solutions For Chapter 2
d) Yt = -5.8 + 4.158 Xt-1 Xt-1 = 3.4 million in years 8 and 9. Substituting gives Yt = -5.8 + (4.158)(3.4) = 8.3372 for sales in each of years 9 and 10. Hence the forecast of total aggregate sales in these years is (8.3372)(2) = 16.6744 or $1,667,440.

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