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The manager of a regional warehouse must decide on the number of loading docks t

ID: 343684 • Letter: T

Question

The manager of a regional warehouse must decide on the number of loading docks to request for a new facility in order to minimize the sum of dock costs and driver-truck costs. The manager has learned that each driver-truck combination represents a cost of $202 per day and that each dock plus loading crew represents a cost of $1,163 per day. Use Table 1 and Table 2.

b. An employee has proposed adding new equipment that would speed up the loading rate to 5.71 trucks per day. The equipment would cost an additional $100 per day for each dock. Should the manager invest in the new equipment?

Yes, because the daily total cost with the new equipment is $______________ which is lower than without the new equipment.

Explanation / Answer

Qa.

Arrival rate (trucks/day)

= 4 trucks per day

Service rate (trucks/day)

µ = 5 trucks per day

Individual dock Utilization

= /µ

= /µ = 4/5 = 0.80

= 0.80

From table, for /µ = 0.80, three dock options are available – 1, 2, and 3 docks

Number of docks

M

Dock cost

Lq (from table)

Ls = Lq + /µ

Driver-truck waiting cost

Cw = Ls x $202

Total cost

= Dock cost + Waiting cost

1

1163

3.2

3.2+0.8

= 4

4*202

= $808

1163+808

= $1971

2

1163*2

= 2326

0.152

0.952

$192.304

$2518.304

3

1163*3

= 3489

0.019

0.819

$165.438

$3654.438

Lowest system cost is $1971 per day for single dock.

Thus, to minimize the cost single dock is required.

Qb.

Arrival rate (trucks/day)

= 4 trucks per day

Service rate (trucks/day)

µ = 5.71 trucks per day

Individual dock Utilization

= /µ

= /µ = 4/5.71 = 0.70

= 0.70

From table, for /µ = 0.70, three dock options are available – 1, 2, and 3 docks

Number of docks

M

Dock cost

Lq (from table)

Ls = Lq + /µ

Driver-truck waiting cost

Cw = Ls x $202

Total cost

= Dock cost + Waiting cost

1

1163+100

= $1263

1.633

2.333525

471.3721296

1734.372

2

2*(1163+100)= 2726

0.098

0.798525

161.3021296

2887.302

3

4089

0.011

0.711525

143.7281296

4232.728

Lowest system cost is $1734.372 per day for single dock, which is less than above option.

Total cost with new equipment = $1734.37

Thus, to minimize the cost new equipment should be used.

Arrival rate (trucks/day)

= 4 trucks per day

Service rate (trucks/day)

µ = 5 trucks per day

Individual dock Utilization

= /µ

= /µ = 4/5 = 0.80

= 0.80