Set 10 due today

• Also c-5 due today

• Thurs (May 16): deadline for late homework (today’s assignments under door BB 4133 Friday before 3PM)

• Final exam Tues May 21 5:30-7:30

• 2 sheets of notes, Scantron

• Sets 1,9,10;C-1;short answer, mult choice

ANSWERS set 10

WAIT LINE

30,24

L=24 30-24

• (1)(a)L=4 people in drug store

(1)(b)Lq

• Lq = 24*24 30(30-24)

• Lq= 3.2

people waiting for service

(1)(c) W= 1 30-24

• W=.167 hr

• Interpret: W = 10 minutes from time you enter drug store until time you leave

(1)(d) Wq

• Wq = 24 30(30-24)

• Wq= .13 hour

• Interpret: 8 minutes before service

(1)(e) U=24/30=.80

• 80% efficiency

• P(server busy)

(1)(f) Po=1-.8=.2

• P(no waiting)

(2) Cost of Waiting

• Av 3 customers arrive per hour(given)

• 10 hours per day(given)

• You compute: 30 customers/day

• Cost of waiting $5 per hour(given)

WAIT COST

(A) (B)

#SERVED/HR 60/5=12 60/10=6

WAIT TIME 3 = .028

12(12-3)

3 = .167

6(6-3)

DAILY WAIT TIME

30(.028)=.83 30(.167)=5

WAIT COST .83(5)=$4.17 5(5)=$25

Labor Cost

(a) (b)

Hourly wage $16 $8

Labor Cost 10(16)=$160 10(8)=$ 80

Total Cost

(a) (b)

Wait 4.17 25

Labor 160 80

Total $164.17 $105=MIN

(3) SIMULATION

ARRIVAL PROB CUMUL ARR RN

0 .13 .13 01 to 13

1 .17 .30 14 to 30

2 .15 .45 31 to 45

3 .25 .70 46 to 70

4 .20 .90 71 to 90

5 .10 1 91 to 00

(3) MAXIMUM UNLOADED

MAX UNL PROB CUMUL RN UNL

1 .03 .03 01 TO 03

2 .12 .15 04 TO 15

3 .40 .55 16 TO 55

4 .28 .83 56 TO 83

5 .12 .95 84 TO 95

6 .05 1 96 TO 00

FIRST 5 DAYS: RN

ARR RN SIM ARR UNL RN SIM UNL

37 2 69 4

77 4 84 5

13 0 12 2

10 0 94 5

02 0 51 3

delay

• Case 1: Demand > Supply Delay = Demand – Supply

• Case 2: Demand < Supply Delay =0

• Next slide: Demand = 2B UNL Supply = UNL

FIRST 5 DAYS

DELAY ARRIV 2B UNL MAX U UNL

0 2 2 4 2

0 4 4 5 4

0 0 0 2 0

0 0 0 5 0

0 0 0 3 0

DAYS 6-10

DELAY ARRIV 2B UNL MAX U UNL

0 1 1 3 1

0 2 2 3 2

0 1 1 1 1

0 2 2 2 2

0 4 4 3 3

DAYS 11-15

DELAY ARRIV 2B UNL MAX U UNL

4-3=1 2 3 3 3

3-3=0 5 5 3 3

5-3=2 4 6 4 4

6-4=2 2 4 3 3

4-3=1 2 3 3 3

Av number delayed per day

Total delayed= 1+2+2+1= 6

Number of days = 15

Av = 6/15= 0.4