• Author / Uploaded
• Timothy Jones

• Categories
• Correlación y dependencia
• Errores y residuos
• Análisis estadístico
• Business
• Negocios económicos

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PROBLEMS 1. The monthly sales for Yazie Batteries, Inc., were as follows: Janu ary 20

Febr uary 21

Mar ch 15

Ap ril 14

M ay 13

Ju ne 16

Ju ly 1 7

Aug ust 18

Septe mber 20

Octo ber 20

Nove mber 21

Dece mber 23

a. Plot the monthly sales data. b. Forecast January sales using each of the following: - Naïve method - A 3-month moving average - A 6-month weighted moving average using 0.1, 0.1,0.1, 0.2, 0.2, and 0.3 with heaviest weights applied on the recent month. - Exponential smoothing using an α=0.3, and a September forecast of 18. - A trend projection. c. Which method would allow you to forecast next March?

2. The Carbondale Hospital is considering the purchase of a new ambulance. The decision will rest partly on the anticipated mileage to be driven next year. The miles driven during the past 5 years are as follows: Year Mileage 1 3,000 2 4,000 3 3,400 4 3,800 5 3,700 a. Forecast the mileage for next (6th year) using a 2-year moving average. b. Find the MAD based on a 2-year moving average. c. Use the weighted moving average with weights of 0.4, and 0.6. What is the MAD?

3. Bus and subway rideship for summer months in London, England is believed to be tied heavily to the number of tourists visiting the city. During the past 12 years, the data on the table has been recorded: Year

1 2 3 4 5

Number of Tourists in (Millions) 7 2 6 4 14

Ridership (in Millions) 1.5 1.0 1.3 1.5 2.5

a. b. c. d. e. f. g.

6 15 2.7 7 16 2.4 8 12 2.0 9 14 2.7 10 20 4.4 11 15 3.4 12 7 1.7 Plot these data, is there a linear relationship between number of tourist and ridership? Develop a regression relationship. What is the expected ridership if 10 Million tourists visit London in a next year? Explain the predicted ridership if there are no tourists at all. What is the standard error of the estimate? What is the model’s correlation coefficient? What does the correlation coefficient mean?

4. Abey Kuruvilla, of Parkside Plumbing, uses 1,200 of a certain spare part that costs $25 for each order, with an annual holding cost of $24. a. Calculate the cost of order sizes of 25, 40, 50, 60 and 100. b. Identify the economic order quantity and consider the implications for making an error in calculating economic order quantity. 5. Lead time for one of your fastest-moving products is 21 days. Demand during the period averages 100 units per day a. What would be the appropriate re-order point? b. How does your answer change if demand during lead time doubles? c. How does your answer change if during lead time drops in a half? 6. M. P. VanOyen Manufacturing has gone out of bid for a regulator component. Expected demand is 700 units per month. The item can be purchased from either Allen Manufacturing or Baker Manufacturing. Their price lists are shown on the table below. Ordering cost is $50, and annual holding cost per unit is $5. Allen Mfg. Baker Mfg. Quantity Unit Price Quantity Unit Price 1-499 $16.00 1-399 $16.10 500- 999 15.50 400-799 15.60 1,000 + 15.00 800 + 15.10 a. What is the economic order quantity? b. Which supplier should be chosen? Why? c. What is the optimal order quantity and the total cost of ordering, purchasing, and holding component? 7. Race One Motor is an Indonesian Car manufacturer. At its largest manufacturing facility, in Jakarta, the company produces subcomponents at a rate of 300 per day, and uses these subcomponents at a rate of 12,5000 per year(of 250 working days per year), and ordering costs are $30 per order.

a. b. c. d.

What is the economic production quantity? How many production runs per year will be made? What will be the maximum inventory level? What percentage of time will the facility will be producing the components?

8. Par, Inc., produces a standard golf bag and a deluxe golf bag on a weekly basis. Each golf bag requires time for cutting and dyeing and time for sewing and finishing, as shown in the following table: Hours required per bag Cutting and Dyeing 1/2 1

Product Standard bag Deluxe bag

Sewing and finishing 1 2/3

The profits per bag and weekly hours available for cutting and dyeing and for sewing and finishing are as follows: Product Standard bag Deluxe bag

Activity

Profit per unit 10 8

Weekly hours available 300

Cutting and dyeing Sewing and 360 finishing Par, Inc., will sell whatever quantities it produces of these two products. a. Find the mix of a standard and deluxe golf bags to produce per week that maximizes weekly profit from these activities. b. What is the value of the profit?

9. Solve the following linear programming model graphically. Minimize costs = 4X1 + 5X2 Subject to: X1 + 2X2 ≥ 80 3X1 + X2 ≥ 75 X1 , X 2 ≥ 0