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**Unformatted text preview: **BCO105 I CMQ101 - SEMESTER 2 2014
ASSIGNMENT 2 —— WEIGHTING 25%
DUE 0900 MONDAY 22 SEPTEMBER 2014 ASSIGNMENT tNSTRUCTIONS: l. to 6. 10. 11. Provide written answers to all five questions, submitted as a Word document. Do
not submit hand—written answers. Ensure that a completed cover sheet is attached to the front of the assignment. A
blank cover sheet accompanies the assignment questions. Assignment answer scripts are to be submitted using the submission link in
Learnline. Do not email answer scripts. Excel spreadsheets should not be used for answers, but can be submitted as
attachments if used for any calculations. Excel attachments wilt not be marked.
Each question is worth 15 marks, for an assignment total of 75 marks. Grades wiil
be posted as a score out of 75 in the Grade Centre. Grade Centre scores will be adjusted at the end of semester to reﬂect the actual
weighting of the assignment (25%). Show ail reasoning for decisions made, formulas used and calculations done in the
written answers. Most marks are awarded for demonstration of correct decision
making in relation to appropriate techniques, and correct interpretations of results
obtained from application of these techniques. Please be aware of the CDU rules governing ptagiarism and collusion. While students are encouraged to discuss the questions among themselves, the final
submitted assignment must be the student's own work. Any answer that is a clear copy of another's work will score zero. Late penalties wili apply to assignments submitted after the nominated deadline,
unless an extension approval has been given in writing by the Head of School of
Business and Accounting before the deadline. Late penalties are at the rate of 5% (5 marks per 100) per day late. Any
assignment submitted more than 14 days after the deadiine will not be marked.
Applications for extension need to satisfy the extension policy guidelines, and
should be forwarded to the Head of School of Business. Please see assessment
area for further instructions. The unit lecturer cannot approve extensions. The unit lecturer cannot provide specific guidance on individual assignment
questions, but can answer general questions regarding the appiicaticn of statistical techniques. ASSIGNMENT QUESTIONS: Question 1: The quatity control manager at a light globe factory needs to estimate the mean life of a
large shipment of energy—saving compact light globes. The historical standard deviation of tight globe life is 250 hours. A random sample 01°64 light globes indicates a sample mean
life of 7,940 hours. (3) Construct a 95% confidence interval estimate of the population mean life of light globes
in this shipment. (b) Do you think that the manufacturer has the right to state that the Eight globes last an
average of 8,000 hours? Explain. (0) Must you assume that the popuiation of light globe life is normaliy distributed? Explain. (d) Suppose that the standard deviation changes to 180 hours. What are your amended
answers in parts (a) and (b)? Question 2: Using the company records for the past 500 working days, the manager of a car
dealership has summarised the number of cars sold per day in the fotlowing tabie: 142 J Number of cars sold per day Frequency of occurrence
i 66 imiméwimimgeim tug—‘3 (a) Form the probabiiity distribution for the number of cars sold per day.
(is) Calcuiate the mean or expected number of cars sold per day. (c) Calcuiate the standard deviation of the number of cars sold per day. Question 3: A company is having a new corporate website devetoped. in the final testing phase the
downioad time to open the new home page is recorded for a large number of computers in
office and home settings. The mean download time for the site is 2.5 seconds. Suppose
that the downioad times for the site are normaify distributed with a standard deviation of
0.5 seconds. if you select a random sample of 30 download times: (a) What is the probability that the sample mean time is less than 2.75 seconds? (b) What is the probability that the sample mean time is between 2.70 and 2.90 seconds? (0) The probability is 80% that the sample mean time is between what two values
symmetrically distributed around the population mean? (d) The probability is 95% that the sample mean time is less than what value? Question 4: The number of shares traded each day on the Australian Stock Exchange (ASX) is
referred to as the voiume of trade. During the 2007/08 financial year the average volume
traded daiiy for the ASX All Ordinaries was 935 miliion with a standard deviation of 262 million. Assume that the number of All Ordinaries shares traded daily on the ASX is a normal
random variable with a mean of 935 million and a standard deviation of 262 million For a
randomly selected day, what is the probability that the volume of trading in these shares is: (a) Beiow 500 million?
(b) Between 750 and 1,000 million?
(0) Below 1,500 million? (d) Above 1,200 million? (e) On 18 September 2008 the All Ordinaries volume of trade was 2,125 million. What is
the probability that the volume of trading for the All Ordinaries on a randomly selected day
is at least 2,125 million? What conclusions can you draw from this probabiiity? Question 5: An education study gives information on the study mode (full—time or part—time) of students studying for a post—school qualification as well as their employment status. This
information is summarised in the following table, expressed in percentages (%) of students enroiled in post—schoo! education: full-time iEmployed part—time r r l 17:4 ‘ a a aNQPWPFFW?W ’ (a) Suppose that you select a full—time student. What is the probabiiity that they are not
emptoyed? (b) Suppose that you know that a student is employed full—time. What is the probability that
they are studying full—time? (o) Are the two events, 'employed fuit—time‘ and 'studying full—time', statistically
independent? Explain. (d) What is the probability that a part-time student is in fuii-time employment? (e) What is the probability that a part—time student is not in full—time employment? ...

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