DSCI 3331 Module 1-3 Quizzes

Consider the following linear programming problem: · Maximize 5X + 6Y · Subject to: · 4X + 2Y <=420 · 1X + 2Y <= 120 · all variables >= 0 Which of the following points (X,Y) is not a feasible corner point?

(120,0)

Infeasibility means that the number of solutions to the linear programming models that satisfies all the problem's constraints is:

0

Consider a project that has an expected completion time of 60 weeks and a standard deviation offive weeks. What is the probability that the project will take anywhere between 60 and 65 weeks to complete?

0.34

At a local fast-food joint, cars arrive randomly at a rate of 3 every 30 minutes. The fast food joint takes an average of 4 minutes to serve each arrival. The utilization factor for this system is:

0.4

A suburban specialty restaurant has developed a single drive-thru window. Customers order, pay, and pick up their food at the same window. Arrivals follow a Poisson distribution while service times follow an exponential distribution. If the average number of arrivals is 6 per hour and the service rate is 2 every 15 minutes, what proportion of the time is the server busy (utilized)?

0.75

The annual demand for a product has been projected at 2,000 units. This demand is assumed to be constant throughout the year. The ordering cost is $20 per order, and the holding cost is 20 percent of the purchase cost. Currently, the purchase cost is $40 per unit. There are 250 working days per year. Whenever an order is placed, it is known that the entire order will arrive on a truck in 6 days. How many units should the company order each time an order is placed if the company wishes to minimize total inventory cost?

100

Consider the following linear programming problem: · Maximize · 4X + 10Y · Subject to: · 3X + 4Y ≤ 480 · 4X + 2Y ≤ 360 · all variables ≥ 0 The feasible corner points are (48,84), (0,120), (0,0), (90,0). What is the maximum possible value for the objective function?

1200

Enrollment in a particular class for the last four semesters has been 120, 126, 110, and 130 (in order from oldest to recent). Develop a forecast of enrollment next semester using exponential smoothing with an alpha = 0.2. Assume that an initial forecast for the first semester was 120.

121.17

Given an activity's optimistic, most likely, and pessimistic time estimates of 4, 14, and 18 days respectively, compute the PERT expected activity time for this activity.

13

Daily demand for newspapers for the last 10 days has been as follows (listed from oldest to newest): 12, 13, 16, 15, 12, 18, 14, 12, 13, 15. Forecast sales for the next day (i.e. day 11) using a two-day moving average.

14

Daily demand for newspapers for the last 10 days has been as follows: 12, 13, 16, 15, 12, 18, 14, 12, 13, 15 (listed from oldest to most recent). Forecast sales for the next day (day 11) using a two-day weighted moving average where the weights are 3 and 1 will be:

14.5

Your company is considering submitting a bid on a major project. You determine that the expected completion time is 130 weeks and the standard deviation is 10 weeks. It is assumed that the normal distribution applies. You wish to set the due date for the project such that there is a 95 percent chance that the project will be finished by this time. What due date should be set?

146.5

Consider the following linear programming problem: · Maximize 12X + 10Y · Subject to: · 4X + 3Y <= 480 · 2X + 3Y <= 360 · all variables >= 0 The maximum possible value for the objective function is:

1520

Consider a project that has an expected completion time of 30 weeks and a standard deviation of 6 weeks. What is the probability that the project will be take more than 42 weeks? (Round answer).

2%

Candy Incorporated stocks bubble gum game cards, an item that has a normally distributed demand during the reorder period with a mean of 12 dozen boxes and a standard deviation of 2 dozen boxes. If it is desirable to experience a stockout only 10 percent of the time, what is the appropriate safety stock?

2.56

Andre Candess manages an office supply store. One product in the store is computer paper. Andre knows that 10,000 boxes will be sold this year at a constant rate throughout the year. There are 250 working days per year and the lead-time is 3 days. The cost of placing an order is $30, while the holding cost is $15 per box per year. How many units should Andre order each time to minimize his annual inventory cost?

200

A suburban specialty restaurant has developed a single drive-thru window. Customers order, pay, and pick up their food at the same window. Arrivals follow a Poisson distribution, while service times follow an exponential distribution. If the average number of arrivals is 6 per hour and the service rate is 2 every 15 minutes, what is the average number of customers in the system?

3.00

Demand for a product is constant, but the lead-time fluctuates. The demand during the lead-time is normally distributed with a mean of 40 and a standard deviation of 4. If the company wishes to maintain a 90 percent service level, about how much safety stock should be held?

5.12

The annual demand of a certain item is 5400 units and the computed EOQ is 900 units. How many orders do they have to make per year?

6

At an automatic car wash, cars arrive randomly at a rate of 7 cars every 30 minutes. The car wash takes exactly 4 minutes. On average, what would the length of the line be?

6.533

At a local fast food joint, cars arrive randomly at a rate of 12 every 30 minutes. Service times are random (exponential) and average 2 minutes per arrival. The average time in the queue for each arrival is

8 mins

Inventory

All of the above

The primary purpose of quantitative models is to

B. help the decision-maker gain insight into the important relationships involved in the decision.

Which of the following is a general rule for crashing activities?

Crash activities with zero slack

An M│M│3 model has Pois At an automatic car wash, cars arrive randomly son arrivals, exponential service times, and two channels.

False

The variance of the project completion time is equal to the sum of the variances of all the activities.

False

Which of the following statements is true about r2?

It is also called the coefficient of determination

Which of the following methods produces a particularly stiff penalty in periods with large forecast errors?

MSE

Which of the following factors is (are) not included in ordering cost?

Obsolescene

A new shopping mall is considering setting up an information desk manned by one employee. Based upon information obtained from similar information desks, it is believed that people will arrive at the desk at the rate of 15 per hour. It takes an average of two minutes to answer a question. It is assumed that arrivals are Poisson and answer times are exponentially distributed.(be consistent with rates!) Find the probability that the employee is idle

Po = 0.50

A constraint that does not affect the feasible region is a:

Redundant constraint

A stockout is a situation that occurs when there is no inventory on hand.

True

Bias tells us whether the forecast tends to be too high or too low.

True

CPM was developed for use in managing projects about which we have good information about activity or task completion times.

True

EVPI (Expected Value of Perfect Information) is a measure of the maximum value of additional information.

True

If we are studying the arrival of automobiles at a highway toll station, we can assume an infinite calling population.

True

On a practical note-if we are using waiting line analysis to study cars passing through a single tollbooth, reneging is probably not an issue.

True

One difficulty in waiting line analysis is that it is sometimes difficult to place a value on customer waiting time.

True

Slack is the time an activity can be delayed without impacting the completion time of the project.

True

The best regression model is a statistically significant model with a high r-square and few variables.

True

The production run model is useful when the inventory is produced/delivered over a period of time.

True

The set of solution points that satisfies all of a linear programming problem's constraints simultaneously is defined as the feasible region in graphical linear programming.

True

Trying various approaches and picking the one that results in the best decision is called the trial-and-error method

True

When looking at the arrivals at the ticket counter of a movie theater, we can assume an unlimited queue.

True

Which of the following is not acceptable as a constraint in a linear programming problem?

X + XY + Y >= 12

In a maximization problem, when one or more of the solution variables and the profit can be made infinitely large without violating any constraints, then the linear program has

an unbounded solution

Extra inventory that is used to avoid stockouts is known as:

safety stock

The term queue discipline describes the:

sequence in which members of the queue are serviced

For an activity with more than one immediate successor activity, its latest-finish time is equal to the

smallest latest-start time among its immediate successors

The critical path is

the longest path in the project network.

Infeasibility in a linear programming problem occurs when...

there is no solution that satisfies all the constraints given