George Mason University
School of Management
OM 210:
STATISTICAL ANALYSIS FOR MANAGEMENT
Prof. Harvey Singer
TEST #2:
Random Variables and Probability Distributions (SAMPLE)
Directions:
Read each problem carefully and answer exactly what is asked.
Complete all
problems and all parts in order.
Show all work.
State all results to problems in complete
sentences.
Be careful to define all symbols, and check your work for units (like dollar
signs) and arithmetic.
Explicitly state all assumptions that were made and all rules that
were used.
Sign the honor code statement on page 2 and return this sheet with
completed exam.
Staple all pages to be submitted in their correct order.
1. A factory manager is considering the feasibility of replacing a particular
machine which is prone to breakdowns.
Repair records indicate the following
probability distribution for the number of breakdowns of this machine per
week:
number of breakdowns
0
1
2
3
4
5
proportion
0.12
0.16
0.18
0.32
0.14
0.08
a.
On average, how many breakdowns of this machine can be expected per
week? What is the standard deviation of breakdowns per week?
b.
What is the chance that there will be no more than one breakdown per
week?
c.
What is the chance that there will be at most three breakdowns per week.
d.
It is estimated that each breakdown costs the company $1,500 in lost
output.
What is the expected value and the range in weekly costs to the
company from the breakdowns of this machine?
2. Thirty percent of the jobs received by a machine shop require welding; the
balance of the jobs are straight machining jobs.
a.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
This is the end of the preview.
Sign up
to
access the rest of the document.
 Spring '08
 SINGER
 Probability distribution, probability density function, Harvey A. Singer, distribution best models, problem questions below.

Click to edit the document details