Get premium membership and access questions with answers, video lessons as well as revision papers.

a)In each of the following three situations, use the binomial, poisson, or normal distribution depending on which is the most appropriate. In each case,...

      

In each of the following three situations, use the binomial, poisson, or normal distribution depending on which is the most appropriate.

In each case, explain why you selected the distribution and draw attention to any feature which supports or casts doubt on the choice of distribution.
Situation 1:
The lifetimes of a certain type of electrical components are distributed with a mean of 800 hours and standard deviation of 160 hours.

Required:
Identify situation 1. (2 marks)
If the manufacturer replaces all components that fail before the guaranteed minimum life time of 600 hours, what percentage of the components have to be replaced?
(3 marks)
If the manufacturer wishes to replace only 1% of the components that have the shortest life, what value should be used as the guaranteed lifetime? (3 marks)
What is the probability that the mean lifetime of a sample of 25 of these electrical components exceeds 850 hours? (2 marks)

  

Answers


Moraa
(a) (i) This is a case of Normal distribution. A normal distribution is one
suited to describe continuous random variables. It is appropriate in many situations where measurement is involved, such as weight, volume, heights of people and the life times of electrical goods. The mean and the standard deviation are also given. Unlike Normal distribution, the PQ Binomial distribution has its mean given as µ = np.

Where P – probability of success. n – number of trials.
Variance for the Binomial distribution d2 = npq.
Where q – is the probability of failure while p and n are as explained above.

The poisson distribution has a constant mean “? ” per unit interval with the variance equal to the mean “x? ”

(ii) For normally distributed function, N(µ,(), the standard values
x(µ
Z =

(
Where ( - is the standard deviation. µ - is the mean. x - is the observation.

600 (800
In this case, Z = = - 1.25

160
And from the normal tables:



-1.25 µ

The area under the curve represents the probability or the proportion of events. In this case, the percentage components to be replaced is 10.3470.








From the normal table, an area of 0.49 under the table corresponds to a Z value of 2.33. But since the Bulb with the shortest life is required, this is below the mean and must take a negative value. The value to be used as the guaranteed lifetime for bulbs, denoted as x, can be obtained from the expression for the Z value of -2.33 as follows:

x (µ
( Z =

d
x (800
( -2.33 =

160
( -2.33 x 160 = x – 800
( 800 – 2.33 x 160 = x
( 427.2

The guaranteed life time should be 427 Hours.

(iv) When all possible samples of size n are drawn from a population mean with a mean µand a standard deviation d, then the means of the samples have a probability distribution known as the sampling distribution of means with mean equal to the population mean µ, and a standard
d deviation = where dis the population standard deviation from which
the samples are drawn.

The standard deviation of the sampling distribution of the mean is known as the standard error of the mean. In this case a sample of size

25 will have a mean x(800Hours and a standard error of the mean =
160 160
( 32.
Then using the standard values, Z = ( 1.56 or 2





0 2

From the Normal table a Z value of 2 corresponds to an area = 0.4772, But we require the probability that it exceeds 850 Hours. This is the area to the Right of Z = 2 which is equal to 0.5 – 0.4772 = 0.023.

,b)(i) This is a case of Binomial distribution. This is because the interest is success or failure and the situation deals with discrete variables and not continuous variables. The probability of success here, is P = 0.15, getting a perishable product. The probability of failure is then q = 1.00 – 0.15 = 0.85.

ii)The commodity will be purchased if not more than 2 perishable items are found in sample of 10. The probability of not more than 2 perishable can be written as:

Probability of 0 perishable, 1 perishable or 2 perishable. The probability of 0 perishable, 1 perishable and 2 perishable are obtained using the binomial expression as follows:

The binomial probability expression states that the probability of event (x) written P(x) = nCxpxqn – x.

Thus:
P(0) = 10C0(0.15)0(0.85)10 = (0.15)0 (0.85)10
!


=
0.1968

P(1) = 10C1(0.15)1(.85)9


= 0.3474

P(2) = 10C2(0.15)2(0.85)8

= 0.2759




0.820

Recall: nCrPr qn-r =
n!
r n(r


P q


(n ( r)! r!
The probability of buying the consignment is 0.820

c)(i) This is a case of Poisson distribution. It deals with discrete variables and the probability of a given number of events happening within a specified time interval. The poisson distribution also deals with success or failure but within a specified time interval. This is poisson distribution with a mean “? ” of 2 per 10 seconds or 0.2 per second.

ii)The probability of an event occurring is computed using the following formula for a poisson distribution.

x (?
? e
P(x) =

x!
The probability of more than 3 cars can be expressed as follows:

P(x>3) = 1 – probability of 0, 1, 2, and 3 cars passing. Using the Poisson formula, we get:
P(0)
=
(1.2) 0 e(0.2
(
0!
0.818

P(1)
=
(0.2) 1 e(0.2
(
1!
0.164

P(2)
=
(0.2) 2 .e(0.2
=
2!
0.016

P(3)
=
(0.2) 3 e(0.2
=
3!
0.0011




0.9991






(Probability of more than 3 cars = 1 – 0.9991
= 0.0009

Moraa orina answered the question on April 2, 2018 at 18:23


Next:  a)Explain briefly the application of calculus to economic models, especially in the context of maximizing contribution and minimizing costs. b)Company A...
Previous: Define the term Ethical Consumption as used in business

View More Economics Questions and Answers | Return to Questions Index


Learn High School English on YouTube

Related Questions


  • a)Explain briefly the application of calculus to economic models, especially in the context of maximizing contribution and minimizing costs. b)Company A...(Solved)


    a)Explain briefly the application of calculus to economic models, especially in the context of maximizing contribution and minimizing costs.


    b)company A sells all its output to company B for Sh. 200 per unit. The cost of the sales per week in company A are given by the function C = 2q2 + 40q + 80 where q is the value of weekly sales. Company B uses the output of company A to manufacture a product whose demand is dependent on the sale price. The revenue per week of company B is given by the function:

    R = 1000q – 16q2 and the cost per week of company B excluding cost of the products bought from company A are given by the function.

    C = 2q2 + 80q + 400
    Company A can restrict the weekly supply of its product to company B, but cannot raise the unit price above Sh. 200. The two companies are considering whether to merge together into a single company.

    Required:
    i)At what weekly sales would company A maximize its profits? What would be the profit or loss of company B if company A were able to supply a profit maximizing quantity of its product each week?

    ii)At what level of weekly sales would company B maximize its profits?

    iii)If the two companies merge into one, what would be the profit maximizing output per week and what would be the weekly profit?

    Date posted: April 2, 2018.  Answers (1)

  • Describe the limitations of the CVP (Cost, Volume and Profit) Analysis(Solved)

    Describe the limitations of the CVP (Cost, Volume and Profit) Analysis.

    Date posted: April 1, 2018.  Answers (1)

  • Describe the competitive strategy by Michael Porter(Solved)

    Describe the competitive strategy by Michael Porter.

    Date posted: April 1, 2018.  Answers (1)

  • Describe the BCG matrix as used as a corporate business portfolio analysis tool(Solved)

    Describe the BCG matrix as used as a corporate business portfolio analysis tool.

    Date posted: April 1, 2018.  Answers (1)

  • Give the factors which determines the gains from international trade(Solved)

    Give the factors which determines the gains from international trade.

    Date posted: April 1, 2018.  Answers (1)

  • Describe the various gains from trade(Solved)

    Describe the various gains from trade.

    Date posted: April 1, 2018.  Answers (1)

  • Case study analysis of communication strategysummarize the communication strategy of your chosen organization, b) analyze the communication strategy of your chosen organization, and c) explain...(Solved)

    In this assignment, you will need to a) summarize the communication strategy of your chosen organization, b) analyze the communication strategy of your chosen organization, and c) explain how you would integrate the communication strategy into the current organization where you work or into a former organization where you have worked.

    A. Summarize the Communication Strategy

    Locate an article that discusses the communication strategies used by your chosen organization. After reading your chosen article, you may find the exercise below to be helpful in developing a summary paragraph. Identify the author(s) of your chosen article, and complete the following exercise:

    [Insert author’s name here] discusses how innovative communication processes have helped [insert name of the organization here] resolve [insert issue here].

    The top reason [insert author’s name here] holds that position is __________.

    A second reason [insert author’s name here] holds that position is __________.

    A third reason [insert author’s name here] holds that position is __________.

    After filling in the blanks, you should have a list of the positions and claims made by the authors about your chosen organization. Shape your notes into a summary paragraph. (Do not simply include the list that you completed in the exercise above.)

    Remember that the summary paragraph is where you will present information from the source. You will provide your analysis and interpretation in the following section of the paper.

    B. Analyze the Communication Strategy

    Be sure to include how the communication strategy impacts the organization on multiple levels. Feel free to use the four levels of sales, services, value chain, and continuous improvement as a model, which was discussed in the case study on the Dell Computer Corporation in the Unit VI Lesson. (Note: Your categories may be different.)

    In the analysis portion of the assignment, discuss any problems (or potential problems) with the communications in your chosen organization, and provide potential solutions based on your research. Include ways that effective management could help to provide a solution.

    C. Explain Integration Techniques

    Finally, explain how this communication strategy could be integrated into your current or former workplace.

    You will need to reference at least two academic sources.

    Use the standard five-paragraph format (introduction/body/conclusion). APA format should be used. The assignment should be a minimum of three pages in length. Content, organization, and grammar/mechanics will be evaluated.

    Date posted: March 31, 2018.  Answers (1)

  • a)Explain the following terms as used in network analysis: i)Backward pass; ii)Crashing; ...(Solved)

    a)Explain the following terms as used in network analysis:
    i)Backward pass;
    ii)crashing;
    iii)Slack;
    iv)Earliest start times;
    v)Critical-path activities;

    b)XYZ Construction Company is building a 250-unit apartment complex in Embakasi, Kenya. The project consists of hundreds of activities involving excavating, framing, wiring, plastering, painting, landscaping and more. Some of the activities must be done sequentially and others can be done simultaneously. Also, some of the activities can be completed faster than normal by acquiring additional resources.

    Required:
    i)How would Quantitative Techniques be used to solve this problem?
    ii)What would be the uncontrollable inputs?
    iii)What would be the decision variables of the model? The objective function?
    The constraints?
    iv)Is the model deterministic or stochastic?
    v)Suggest assumptions that could be made so simplify the model.

    Date posted: March 31, 2018.  Answers (1)

  • Your firm is the auditor of Trent Textiles Ltd, and you are planning your audit work on the stock-take, which will be carried out at...(Solved)

    Your firm is the auditor of Trent Textiles Ltd, and you are planning your
    audit work on the stock-take, which will be carried out at the firm‟s year-
    end of 31 May 19X3.
    Trent Textiles manufactures knitted garments, including pullovers. The
    production process comprises:
    (a) Knitting the individual components (e.g body and arms);
    (b) Sewing the components together to form the finished garment;
    (c) Cleaning, finishing, pressing and folding the garments;
    (d) Packing the garments, ready for dispatch to the customer.
    Trent Textiles does not have a perpetual inventory system, so the value of
    the stock in the accounts is found from the stock-take at the year-end. For
    management purposes, Trent Textiles carries out a full stock-take every
    three months.
    Your permanent file of the company confirms that it has a single factory
    and no internal audit department.
    You have been asked by the manager in charge of the audit to suggest the
    work you will perform at the stages listed below.
    Required:
    (a) State the work you will carry out prior to the commencement of the
    stock-take.

    (b) State the procedures you will check during the stock-take to ensure
    the company‟s staff have accurately recorded the stock.

    (c) State the work you will carry out and the matters you will record at the
    stock-take

    Date posted: March 30, 2018.  Answers (1)

  • In auditing the financial statements of companies which use computerized accounting systems, the auditors may find that this traditional (audit) trail is often obscured. Various...(Solved)

    In auditing the financial statements of companies which use computerized
    accounting systems, the auditors may find that this traditional (audit) trail is
    often obscured. Various techniques can be used in order to give the
    auditors greater assurance when the audit trail is lost.
    Required;
    a) Explain why there is a possible loss of audit trail when companies
    utilize computerized accounting systems and why auditing through
    the computer assists the auditors in overcoming this loss of audit
    trail.
    b) Explain how the auditors can use analytical procedures in order to
    give them greater assurance when there is a loss of audit trail.

    c) Outline how audit software can be used by the auditors in order to
    assist them in carrying out their analytical procedures.

    d) Explain the possible reasons and implications (audit) of significant
    changes in the following ratios when compared to the prior years
    ratios:
    i. The debtors turnover ratio has decreased over the year.
    ii. The stock turnover ratio has decreased from the previous year‟s
    rate.

    Date posted: March 30, 2018.  Answers (1)

  • (a) Define tests of controls, substantive procedures and walk-through tests. (b) Explain how assessment of systems and controls impacts upon the main stages of the...(Solved)

    a) Define tests of controls, substantive procedures and walk-through
    tests.
    (b) Explain how assessment of systems and controls impacts upon the
    main stages of the audit process
    (c) Explain the role that internal control questionnaires and internal
    control evaluation questionnaires play in determining the effectiveness
    of the systems of internal control.

    Date posted: March 30, 2018.  Answers (1)

  • What are the common characteristics of less developed countries?(Solved)

    What are the common characteristics of less developed countries?

    Date posted: March 29, 2018.  Answers (1)

  • Explain why countries engage in international trade(Solved)

    Explain why countries engage in international trade.

    Date posted: March 29, 2018.  Answers (1)

  • The following are common errors that students make when discussing supply and demand. What is the mistake in each? (i) At equilibrium, demand equals supply (ii) The quantity of...(Solved)

    The following are common errors that students make when discussing supply and demand. What is the mistake in each?
    (i) At equilibrium, demand equals supply.
    (ii) The quantity of demand is greater than the quantity of supply
    (iii) They move along the line from both ends to an equilibrium in the middle
    (iv) The increase in demand causes an increase in supply

    Date posted: March 27, 2018.  Answers (1)

  • After hurricane Andrew hit Florida and Louisiana, consumers expressed outrage at the high prices being charged for chainsaws, generators and bottled water. If government followed...(Solved)

    After hurricane Andrew hit Florida and Louisiana, consumers expressed outrage at the high prices being charged for chainsaws, generators and bottled water. If government followed consumers’ demands and imposed price ceilings in these markets, what is likely to be the result?

    Date posted: March 27, 2018.  Answers (1)

  • (The Meaning of Full Employment) When the economy is at full employment, is the unemployment rate at zero percent? Why or why not? How would...(Solved)

    (The Meaning of Full Employment) When the economy is at full employment, is the unemployment rate at zero percent? Why or why not? How would a more generous unemployment insurance system affect the full employment figure?

    Date posted: March 25, 2018.  Answers (1)

  • Write short notes on the concept of quasi-rent?(Solved)

    Write short notes on the concept of quasi-rent?

    Date posted: March 25, 2018.  Answers (1)

  • Define wages and discuss the various kinds of labour?(Solved)

    Define wages and discuss the various kinds of labour?

    Date posted: March 25, 2018.  Answers (1)

  • Define trade union.What are the main objectives of trade union?(Solved)

    Define trade union.What are the main objectives of trade union?

    Date posted: March 25, 2018.  Answers (1)

  • Discuss the factors that affect relative wages(Solved)

    Discuss the factors that affect relative wages.

    Date posted: March 25, 2018.  Answers (1)