View the step-by-step solution to: It is known from past experience that the life of a machine

It is known from past experience that the life of a machine component is approximately normally distributed with mean equal to 200 hours and a standard deviation of 4 hours. Calculate the probability that a randomly selected componet has a life of a)at least 206 hours b) between 204 hours and 208hours.
B com- B St ass-1(2011).pdf

Degree
January 2011

Assignment
Business statistics

Botswana College of Distance and Open Learning
I n Collaboration with

Z imbabwe Open University

B ACHELOR OF COMMERCE

B USINESS STATISTICS
( Module S TAT102 )

A ssignment 1 , 2011
( Covers Unit 1 to 7)
M arks 100
- --------------------------------------------------------------------------------------------

I nstruction to Learners :

1) The assignment consists of 2 Sections A and B.
2) Answer all questions in section A, and B.
3) Begin every question on a new page.
4) Marks are given against the questions.

Bocodol College of Open and Distance Learning
Assignment 1, 2010

Page 1 of 1

Degree
January 2011
S ECTION A ( Answer al l questions in this section).

Assignment
Business Statistics
[ 15 m arks]

1. Which is the correct order through which data is made more meaningful
(a) Collection, processing, Summarizing, and Interpretation
(b) Processing, collection, Summarizing, and Interpretation
(c) Interpretation, collection , processing, and summarizing
(d) Summarizing, Collection, processing, and interpretation

2. Which of the following is NOT a measure of variability?
(a) Median
(b) Variance
(c) Standard deviation
(d) Range

3. In a right-skewed distribution
(a) the median equals the arithmetic mean.
(b) the median is less than the arithmetic mean.
(c) the median is larger than the arithmetic mean.
(d) none of the above.

4. A survey was conducted to determine how people rated the quality of programming
available on television. Respondents were asked to rate the overall quality from 0
(no quality at all) to 100 (extremely good quality). The stem-and-leaf display of the
data is shown below. Table 4
Stem Leaves
3
24
4
03478999
5
0112345
6
12566
7
01
8
Botswana College of Open and Distance Learning, 2011

Page 2 of 2

Degree
January 2011

Assignment
Business Statistics
9

2

Referring to Table 4, what percentage of the respondents rated overall television
quality with a rating of 80 or above?
(a) 0
(b) 4
(c) 96
(d) 100

5. Referring to Table 4, what percentage of the respondents rated overall television
quality with a rating of 50 or below?
(a) 11
(b) 40
(c) 44
(d) 56
6. Which of the following divides a group of data into four subgroups?
(a) Quartile
(b) Percentiles
(c) standard deviation
(d) Median
7. Which of the following is a non-probability sampling procedure?
(a) Simple random sampling
(b) Stratified random sampling
(c) Quota sampling
(d) Cluster sampling
8. The width of each bar in a histogram corresponds to the
(a) differences between the boundaries of the class.
(b) number of observations in each class.
(c) midpoint of each class.
(d) percentage of observations in each class.
9. Which one of the following is affected by extreme scores ?
Botswana College of Open and Distance Learning, 2011

Page 3 of 3

Degree
January 2011

Assignment
Business Statistics

(a) Mean
(b) Median
(c) Mode
(d) Range
9. In a research study, the following variables were measured on each
sex, initial weight(g), body temperature (C), weight gain(g).
The scale of these four variables (in order) are:
(a) Nominal, ratio, ratio, ratio
(b) Nominal, ratio, interval, interval
(c) Ordinal, ratio, interval, ratio
(d) Nominal, ratio, interval, ratio
10. A student discovers that his grade on a recent test was the 72nd percentile. If 90
students wrote the test, then approximately how many students received a higher
grade than he did?
(a) 65
(b) 25
(c) 72
(d) 71
11. The chance that a person will contract AIDS after a sexual contact with
an infected partner has been estimated to be 1/4. This means:
(a) A person will be infected after exactly 4 sexual contacts with infected
partners.
(b) Of 1000 people having sexual contacts with infected partners, exactly 250
will become infected.
(c) Of 200 people having sexual contacts with infected partners, about 50 will
become infected.
(d) In exactly 25% of all sexual contacts with infected partners, the infection
will spread.

Botswana College of Open and Distance Learning, 2011

Page 4 of 4

Degree
January 2011

Assignment
Business Statistics

12. Marks on a Business statistics test follow a normal distribution with a mean of 65
and a standard deviation of 12. Approximately what percentages of the students
have scores below 50?
(a) 11%
(b) 89%
(c) 15%
(d) 18%
1 3. Which of the following is NOT an assumption of the Binomial distribution?
(a) All trials must be independent.
(b) Each trial must be classified as a success or a failure.
(c) The number of successes in the trials is counted.
(d) The probability of success is equal to .5 in all trials
14. Which of the following is NOT applicable to a Poisson Distribution?
(a) It is used to compute the probability of rare events.
(b) Every event is independent of every other event.
(c) It is parameterized by the sample size and the probability that an event will
occur.
(d) The theoretical range for the number of events that could occur is 0,1,2,3, ...
15. The nonrandom sampling type that involves selecting a convenience sample from a
population with a specific set of characteristics for your research study is
called_____.
(a) Convenience sampling
(b) Quota sampling
(c) Purposive sampling
(b) Snowball sampling

Botswana College of Open and Distance Learning, 2011

Page 5 of 5

Degree
January 2011

Assignment
Business Statistics

S ECTION B

Q uestion 2

[ 9 m arks]

(i)

Classify the following sets of data as qualitative or quantitative. If it is quantitative,
further categorizes the data into discrete or continuous
[ 5].

(a)
(b)
(c)
(d)
(e)

Monthly salary of teachers in a school.
Types of car driven by lecturers at University of Botswana.
The religious affiliations of college students
Number of houses owned by Botswana Housing Corporation.
Student s evaluation (Poor, Unsatisfactory, Satisfactory, Good and Excellent)

(ii)

State whether the data from the following statement is nominal, ordinal,
interval or ratio.
(a)

The normal operating temperature of a car engine.

(b)

Speakers of a seminar rated as excellent, good, average or

(c)

The monthly salary of school teachers.

(d)

The number of papaya fruits harvested per day by a farmer in
Sekinchang,

(e)

Classification of students using academic program.

Q uestion 3
Botswana College of Open and Distance Learning, 2011

poor.

[5]

[ 1 5 marks]
Page 6 of 6

Degree
January 2011

Assignment
Business Statistics

(i) The following shows the area and the various types of land or water in a certain
country.
(j)
Type
Area (km2)

Urban
30

Jungle
150

Farmland
120

River or lake
200

The pie chart for above data is attached below.

Pie Chart of Various Types of Land or Water in A Certain
Country

Urban
6%
River or lake
40%

Jungle
30%
Urban

Farmland
24%

Jungle
Farmland
River or lake

Refer to the given information and chart and write a brief report.

[3]

(ii) A research physician conducted a study on the ages of persons with diabetes. The
following data were obtained for the ages of a sample of 35 diabetics:
48
4 1 57
83 41 55
59
Botswana College of Open and Distance Learning, 2011

Page 7 of 7

Degree
January 2011

Assignment
Business Statistics
61
54
64
10

38 48
23 47
45 53
60 83

79
56
82
76

75
79
68
21

77
68
38
65

7
61
70
47

(a) Construct a frequency distribution using classes of equal width,
beginning with the class, 0-9, 10 19, 20 29, .
[4]
(b) Using the frequency distribution in (a), construct a more than Ogive .
[4]
(c) Use the diagram in (b) and determine the median, 25th percentile and 75th
percentile.
[ 2]
(d) Which is the most suitable measure of central tendency we should report?
Why?
[2]
Q uestion 4

[ 2 5 m arks ]

( i ) The following data is the daily wages of 80 workers in a Murray and Roberts s
construction company.
Daily Wages (P)

Number of workers

10 19

6

20 29

10

30 39

30

40 49

20

50 59

10

60 - 69

4

T otal

80

(a) Find the mean, median and mode.
(b) Find the first quartile, Q1 and third quartile, Q3.
(c) Find the variance and standard deviation.
(d) Draw a histogram
(e) What is the shape of distribution for this data? What is the most suitable
Botswana College of Open and Distance Learning, 2011

[9]
[4]
[4]
[ 4]

Page 8 of 8

Degree
January 2011

Assignment
Business Statistics

central tendency and measure of spread for this data? Why?es

Q uestion 5

[ 4]

[ 9 m arks]

In response to nutrition concerns raised last year about food served in school
cafeterias, the district council entered into a one-year contract with the Healthy
Alternative Meals (HAM) Company. Under this contract, the company plans and
prepares meals for 2,500 Primary school, junior secondary school, and senior
secondary students, with a focus on good nutrition. The school administration
would like to survey the students in the district to estimate the proportion of
students who are satisfied with the food under this contract.
Two sampling plans for selecting the students to be surveyed are under
consideration by the administration. One plan is to take a simple random sample
of students in the district and then survey those students. The other plan is to
take a stratified random sample of students in the district and then survey those
students.
(a) Describe a simple random sampling procedure that the administrators could
use to select 200 students from the 2,500 students in the district.
[ 3]
(b) If a stratified random sampling procedure is used, give one example of an
effective variable on which to stratify in this survey. Explain your reasoning.

[ 3]

(c) Describe one statistical advantage of using a stratified random sample over
a simple random sample in the context of this study.

[ 3]

Q uestion 6
(i)

[ 15 m arks]

It is known from past experience that the life of a machine component is
approximately normally distributed with mean equal to 200 hours and a

Botswana College of Open and Distance Learning, 2011

Page 9 of 9

Degree
January 2011

Assignment
Business Statistics

standard deviation of 4 hours. Calculate the probability that a randomly
selected component has a life of
(a) at least 206 hours.
(b) Between 204 hours and 208 hours.
(ii)

[ 3]
[ 4]

A random sample of 80 lawyers was taken, and they were asked if they
are in favor of or against Corporal punishment in schools. The following
table gives the two-way classification of their responses.
Favors Capital
Punishment

Opposes Capital
Punishment

Male

32

24

Female

13

11

If one lawyer is randomly selected from this group, find the probability that this
lawyer:
(a) favors capital punishment

[2]

(b) is a female

[2]

(c) opposes capital punishment given that the lawyer is a female

[2]

(d) Opposes capital punishment or is a female.

[2]

Q uestion 7
(i)

[ 12 m arks]

In an office, three secretaries process incoming copies of a certain form.
The first secretary processes 40%, the second secretary processes 35 %.

Botswana College of Open and Distance Learning, 2011

Page 10 of 10

Degree
January 2011

Assignment
Business Statistics

The third secretary processes 25%. The first secretary has an error rate of
0.04, the second has an error rate of 0.06, and the third has an error rate of
0.03%. A form selected at random from a day s output is found to have an
error. The supervisor wishes to know the probability that it was processed
by the first secretary.
[ 3]
(ii) If the probability that any one person requires medical attention in one
particular year is 0.25, what is the probability that:
(i) four people live through the year without medical attention?
(ii) just one of the four needs medical attention?
(iii) at least two of the four require medical attention?

[ 3]

(iii) A rail company knows that on average they will have 2 people ill each day. In order
to make plans for replacements they have asked you to calculate the following
probabilities.
In a single day
(i)
No employees ill
(ii)
Two or less employees ill
(iii)
Four or more employees ill

Botswana College of Open and Distance Learning, 2011

[ 3]

Page 11 of 11

Sign up to view the entire interaction

Why Join Course Hero?

Course Hero has all the homework and study help you need to succeed! We’ve got course-specific notes, study guides, and practice tests along with expert tutors and customizable flashcards—available anywhere, anytime.

-

Educational Resources
  • -

    Study Documents

    Find the best study resources around, tagged to your specific courses. Share your own to gain free Course Hero access or to earn money with our Marketplace.

    Browse Documents
  • 890,990,898

    Question & Answers

    Get one-on-one homework help from our expert tutors—available online 24/7. Ask your own questions or browse existing Q&A threads. Satisfaction guaranteed!

    Ask a Question
  • 890,990,898

    Flashcards

    Browse existing sets or create your own using our digital flashcard system. A simple yet effective studying tool to help you earn the grade that you want!

    Browse Flashcards