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CPA
Foundation Leval
Quantitative Analysis September Pilot 2015
Suggested solutions

Quantitative analysis
Revision Kit

QUESTION 1(a)

Q Highlight any four assumptions of Markov Analysis.
A

Solution


Assumptions of Markov Analysis:


  • The system being analyzed can be divided into distinct states.
  • The process moves from one state to another in a series of discrete steps.
  • The probability of transitioning from one state to another remains constant over time.
  • The Markov property holds, meaning the future state depends only on the current state and not on the sequence of events that preceded it.
  • Transitions between states are mutually exclusive.
  • There is a well-defined starting point and ending point in the system.
  • The Markov chain has a finite number of states.



QUESTION 1(b)

Q The research industry in your country has three market research firms namely X, Y and Z which provide research services. The following data has been collected in relation to the flow of clients among the three firms:

Number
of clients
Market
Share
Flow of clients Number
of clients
Market
Share
Gains from Losses to

X
Y
Z
31.12.2013
408
832
1,062

0.177
0.361
0.461
X
-
30
18
Y
24
-
14
Z
40
10
-
X
-
24
40
Y
30
-
10
Z
18
14
-
31.12.2014
424
834
1044

0.184
0.362
0.454

Required:
(i) Convert the above data into a matrix of transition probabilities.

(ii) Estimate each firm's market share for 2015.
A

Solution


i) Converting the above data into a matrix of transition probabilities


Calculating the percentage of retention and transfer:

Percentage of retention:

Firm proportion %

X → (408 - 30 - 18) / 408 = 0.882

Y → (832 - 24 - 14) / 832 = 0.954

Z → (1062 - 40 - 10) / 1062 = 0.953

Proportion of transfers a,ong the firms

To

From
X Y Z
X - 30/408 = 0.074 18/408 = 0.044
Y 24/832 = 0.029 - 14/832 = 0.017
Z 40/1062 = 0.038 10/1062 = 0.009 -


Matrix of transition position is

0
X
Y
Z
[
X
0.882
0.029
0.038
Y
0.074
0.954
0.009
Z
0.044
0.017
0.953
]


(ii) Estimate each firm's market share for 2015.


Vector matrix of the current market share

0
X
[0.184
Y
0.362
Z
0.454]
[
X
0.882
0.029
0.038
Y
0.074
0.954
0.009
Z
0.044
0.017
0.953
]


X
Y
Z
[
0.184(0.882) +
0.184(0.074) +
0.184(0.044) +
0.362(0.029) +
0.362(0.954) +
0.362(0.017) +
0.454(0.038)
0.454(0.009)
0.454(0.953)
]


X
Y
Z
[
0.190
0.363
0.447
]


The firms market share for 2015

Firm No.of clients Market share
X
Y
Z
437
836
1029
0.190
0.363
0.447
Total 2302 1.000




QUESTION 1(c)

Q A firm has a linear demand function for its product. When the price of the product is Sh. 220, the quantity demanded is 40 units. When the price increases to Sh. 240 the quantity demanded becomes 30 units. In addition, the firm's marginal cost function is given by:

MC = 40q-2q²+2

Fixed cost = Sh. 5million

where q = quantity demanded, MC = marginal cost (in Sh. million)

Required:
(i) The level of output that maximises profits.

(ii) The maximum profit.

(iii) The price of the product at the maximum profit.

(iv) The price elasticity of demand when the profit is at the maximum (interpret your result).
A

Solution


(i) The level of output that maximizes profit


Demand function; P = a + bq

Therefore;

220 = a + 40b......i
240 = a + 30b......ii

-20 = 10b

b = -2

a = 220 - 40(-2) = 300

P = 300 - 2q

Where;

P = unit selling price

Total revenue (TR) - pq = (300 - 2q)q

TR = 300q - 2q2

Marginal Revenue (MR) = dTR / dq = 300 - 4q

At maximum profit;

MC = MR

Therefore,

40q - 2q2 + 2 = 300 - 4q

-2q2 + 44q = 298

q² - 22q + 149 = 0

q
=
-b ± √b² - 4ac

2a

q
=
-(-22) ± √-22² - 4 x 1 x 149

2 x 149

q
=
-(-22) ± √-112

2 x 149

Since the expression inside the square root is negative, it means there are no real roots for this quadratic equation. In other words, the equation has no real solutions. This implies that there is no real value of q that satisfies the equation, and therefore, there is no quantity that maximizes profit based on the quadratic equation.

(ii) The maximum profit.


(iii) The price of the product at the maximum profit.


(iv) The price elasticity of demand when the profit is at the maximum (interpret your result).






QUESTION 2(a)

Q The City Theatre has four auditoriums namely C1, C2, C3 and C4. Each auditorium performs a different play at any given time. The performances start at different times to avoid long queues that would occur if all the auditoriums were to start performance at the same time. The theatre has a single ticket booth and a cashier who can maintain an average service rate of 280 patrons per hour. Arrivals are poisson distributed at an average of 210 patrons per hour. The services are assumed to follow an exponential distribution.

Required:
(i) The average number of patrons waiting in line to purchase the tickets.

(ii) The average time spent waiting in line to get to the ticket, window.

(iii) The average time a patron spends in the system.

(iv) The percentage of time the cashier is busy.

(v) The probability that there are more than two people in the system.
A

Solution


i) The average number of patrons waiting in line to purchase the tickets


Service rate μ = 280 patrons per hour

Arrival rate λ = 210 patrons per hour

Therefore,

Lq
=
λ2

μ(μ - λ)


Lq
=
2102

280(280 - 210)


44,100 / 19,600 = 2.25 = 2 patrons

(ii) The average time spent waiting in line to get to the ticket.


Wq
=
λ

μ(μ - λ)


Wq
=
210

280(280 - 210)


= 0.01071 hours

(iii) The average time a patron spends in the system.


Ws
=
1

μ - λ


Ws
=
1

280 - 210


1 / 70 = 0.0143 hrs

(iv) The percentage of time the cashier is busy.


e = λ / μ = 210 / 280

0.75 or 75%

(v) The probability that there are more than two people in the system.


P(n>k) = [ λ / μ ]k+1

λ = 210 ,μ = 280 ,k = 2

P(n>2) = [ 210 / 280 ]2+1

= (0.75)3

0.421875 or 42.19%




QUESTION 2(b)

Q A marketing firm employs part-time marketers. The hours worked and the earnings of ten such marketers are as shown below:

Marketer
Hours worked (x)
Earnings (Sh. “000”) (y)
1
20
5.5
2
30
7.4
3
48
11.0
4
39
9.3
5
28
7.2
6
14
4.3
7
60
13.5
8
50
12.0
9
62
14.0
10
43
10.0

Required:
(i) The least squares regression function relating the hours worked and earnings. Interpret your results.

(ii) The Spearman's rank correlation coefficient. Comment on your result.
A

Solution


(i) The least squares regression function relating the hours worked and earnings. Interpret your results.


y = a + bx

a
=
Σy

n
-
bΣx

n


b
=
nΣxy - ΣxΣy

nΣx2 - (Σx)2


X Y"000" XY X2
20 5.5 110 400
30 7.4 222 900
48 11 528 2,304
39 9.9 362.7 1,521
28 7.2 201.6 784
14 4.3 90.2 196
60 13.5 810 3,600
50 12 600 2,500
62 14 868 3844
43 10 430 1849
394 94.2 4,193.5 17,898


n = 10

b
=
10(4,193.5) - 394(94.2)

10(17,898) - (394)2


4,820.2 / 23,744 = 0.203

a
=
94.2

10
-
0.203
x
394

10


9.42 - 7.9982 = 1.4218

Y = 1.4218 + 0.203x

Interpretation of the above regression equation:

a = Sh. 1,421.80. This represents the fixed earnings
b = Sh.203.00. This represent the earnings per hour.

(ii) The Spearman's rank correlation coefficient. Comment on your result.


r
= 1 -
6∑d²

n(n² - 1)


X Y Rx Ry d = Rx - Ry d2
20
30
48
39
28
14
60
50
62
43
5.5
7.4
11
9.3
7.2
4.3
13.5
12
14
10
9
7
4
6
8
10
2
3
1
5
9
7
4
6
8
10
2
3
1
5
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0


r
= 1 -
6∑0²

10(10² - 1)
= 1


The results indicate a perfect positive association between the hours worked and the earnings of the marketers in the marketing firm. The positive rank correlation coefficient of 1 suggests a strong and direct relationship, implying that as the hours worked increase, the earnings also increase proportionally.




QUESTION 3(a)

Q Lanex Company specialises in the production of an industrial dye. The firm manufacturers two types of dyes; light and dark. The selling price and the unit variable costs for the dyes are shown below:


Production
Light
Dark
Selling price
(Sh.) per litre

13.00
16.00
Unit variable cost
(Sh.) per litre

9.00
10.00

Each litre of light dye requires 6 minutes of skilled labour and each litre of dark dye requires 12 minutes of skilled labour.

In a given day, there are 400 man hours of skilled labour available. There are also 100 grammes of an important blending chemical available each day, where each litre of light dye requires 0.05 grammes of the blending chemical and each litre of dark dye requires 0.02 grammes of the chemical

The processing capacity at the plant is limited to 3,000 litres of dye per day.

The company is committed to supply a leading retailer with 5.000 litres of light dye and 2,500 litres of dark dye each working week (consisting of five days). In addition, there is an agreement with the unions that at least 2,000 litres should be produced each day.

Lanex company's management would like to determine the daily production volume for each of the two dyes that will maximise total contribution.

Required:
(i) A linear programming model of the production problem facing Lanex company.

(ii) Using the graphical approach, determine the optimum daily production plan and consequent contribution
A

Solution


(i) A linear programming model of the production problem facing Lanex company.


The objective:

To determine the daily production volume for each of the two dyes that will maximize contribution.

Contribution per unit of

Light = 13 - 9 = Sh.4 per unit

Dark = 16 - 10 = Sh.6 per unit

The objective function = Zmax = 4𝑥 + 6y

Subject to constraints:

Skilled labour hour constraints;

6𝑥 / 60 + (12 / 60)y ≤ 400

Therefore, 0.1𝑥 + 0.2 y ≤ 400

Blending chemical gramme constraint;

0.05𝑥 + 0.02y ≤ 100

Processing capacity constraint;

𝑥 + y ≤ 3000

Production capacity constraint;

𝑥 + y ≥ 2000

(ii) Using the graphical approach, determine the optimum daily production plan and consequent contribution.




Non negativity constraint
X ≥ 0
Y ≥ 0
Where;

𝑥 = Number of units of litres of product "light" to be manufactured
Y = Number of units or litres of product "dark" to be manufactured

Hence the optimal dail production plan is

X = 1500 litres of light dye
Y = 1250 litres of dark dye

Optimal contribution:

Zmax = 4(1,500) + 6(1,250) = 6,000 + 7,500

Sh 13,500 per day





QUESTION 3(b)

Q Brightshine Limited based in Nairobi manufactures a detergent. The firm is considering opening a new plant in Nakuru. The opening of a new plant will, however, depend on the demand for the detergent in Nakuru.

Information concerning the demand for the detergent is shown below:

H - High demand and leads to a profit of Sh.6,000,000 per year.

M - Moderate demand and leads to a profit of Sh.1,500,000 per year.

L - Low demand and leads to a loss of Sh.2,500,000 per year.

The chances of having high, moderate and low demand are assessed at 30%, 30% and 40% respectively by the firm's management.

A market research group could be employed to provide information on which market demand would be realised. Past experience with work in the same market with this group shows its information cannot be relied upon to be absolutely accurate.

The market research group classifies its results as either being good prospects (G) or poor prospects (P). The table below gives the extent of reliability of this market research group:

Market survey Actual state of nature
Result
G
P
H
0.7
0.3
M
0.6
0.4
L
0.2
0.8

The market research group would charge a fee of Sh.60,000 if it was hired.

Required:
(i) The best course of action on the basis of prior information.

(ii) The expected value of perfect information.

(iii) Advise Brightshine Limited whether the market research should be conducted. Show your workings using a decision tree
A

Solution


(i) The best course of action on the basis of prior information


The best course of action is to open a new plant when the demand is high (H) because it results in the highest profit. -

(ii) The expected value of perfect information (EVPI)


The Expected Value of Perfect Information (EVPI) represents the maximum amount a decision-maker should be willing to pay for perfect information before making a decision under uncertainty. It is the difference between the expected value of making a decision without perfect information and the expected value of making a decision with perfect information.

EVPI = EMVwith perfect information − EMVwithout perfect information

Where:

EMV stands for Expected Monetary Value,

with perfect information refers to the scenario where perfect information is available,

without perfect information refers to the scenario where the decision is made without perfect information.

EMVwith perfect information

0.30(6000,000) + 0.3(0) = Shs 1,800,000

Payoff matrix table

State of demand
High(H) Moderate(M) Low(L)
Decision alternative
Open new plant
Do nothing
0.3
6,000,000
0
0.3
1,500,000
0
0.4
-2,500,000
0


EMVwithout perfect information

0.30(6000,000) + 0.30(1,500,000) + 0.40(-2500,000)

1800,000 + 450000 - 1,000,000 = Sh. 1,250,000

EVPI = 1,800,000 - 1,250,000 = 550,000

(iii) Advise Brightshine Limited whether the market research should be conducted. Show your workings using a decision tree.


Revision of prior probabilities by use of contingent table

State of nature
High(H) Moderate(M) Low(L) Total
0.30 0.30 0.40
Market Survay
Report
G (0.7 | 0.6 | 0.2)
P (0.3 | 0.4 | 0.8)
(0.7 x 0.3) = 0.21
(0.3 x 0.3) = 0.9
(0.6 x 0.3) = 0.18
(0.4 x 0.3) = 0.12
(0.2 x 0.4) = 0.08
(0.8 x 0.4) = 0.32
0.47
0.53
Total 0.3 0.3 0.4 1.0


Therefore,

P(H / G) = 0.21 / 0.47 = 0.45

P(M / G) = 0.18 / 0.47 = 0.38

P(L / G) = 0.08 / 0.47 = 0.17

Total = 1.00

P(H / P) = 0.09 / 0.53 = 0.17

P(M / P) = 0.12 / 0.53 = 0.23

P(L / P = 0.32 / 0.53 = 0.60

Total = 1.00



Therefore,

Expected value with perfect information EVwPI = Sh 1,265,600

Expected value of sample information EVI = 1265,600 + 6000 - 1250,000 = Sh. 75,600

Hence, Brightshine Itd should conduct the market research since the cost is less than the amount that it would incur if it were to conduct a market study




QUESTION 4(a)

Q Distinguish between the following sets of terms:

(i) Zero-sum game and non-zero sum game.

(ii) Pure strategy game and Mixed strategy game.
A

Solution


(i) Distinguishing Zero-sum game and Non-zero sum game:


Zero-sum game: In a zero-sum game, the total amount of wealth or utility in the system remains constant. Any gain by one participant is offset by an equal loss by another participant.

Non-zero sum game: In a non-zero sum game, the total amount of wealth or utility can change, and the participants can collectively win or lose. Cooperation and coordination can lead to outcomes where all participants gain.


(ii) Distinguishing Pure strategy game and Mixed strategy game:


Pure strategy game: In a pure strategy game, players choose a specific action or strategy with certainty. There is no randomness in the decision-making process.


Mixed strategy game: In a mixed strategy game, players choose their strategies based on a probability distribution. The decision-making involves randomness, and players may use a mix of different strategies with certain probabilities.





QUESTION 4(b)

Q An engineering firm is tendering for a contract to supply a steel fabrication. The tasks have been analysed as follows:

Activity
A
B
C
D
E
F
G
H
I
J
K
L
M
Predecessory activity
-
-
A
A
A
A,B
C
C,D
E
G,H
H
H,I
H,I,F
Time(Days)
10
12
10
9
13
17
12
14
13
12
10
14
13

Required:
(i) A network diagram for the project.

(ii) The critical path and the expected project duration.

(iii) The time schedules for activities F, G and H.
A

Solution


(i) A network diagram for the project.



(ii) The critical path and the expected project duration.


A - E - I - L

Duration → 50 days

(iii) The time schedules for activities F, G and H.


Earliest start (ES) = EF of the one before it

Earliest finish (EF) = ES + Duration of the activity

Latest Finish LF = is the smallest of the start times for the next activity.

Latest Start (LS) = LF − Duration of the activity

Float = LS - ES or LF - EF

Activity F: ES = 12, EF = 29, LS = 19, LF = 36, Float = 7

Activity G: ES = 20, EF = 32, LS = 22, LF = 34, Float = 2

Activity H: ES = 20, EF = 34, LS = 20, LF = 34, Float = 0



QUESTION 5(a)

Q A machine is composed of three components X, Y and Z. The probability that component X is in good working condition is 7/10. If component X is in good working condition, the probability that component Y is in good working condition is 3/5. If component X is not in good working condition, the probability that component Y is in good working condition is 1/3. If components X and Y are in good working condition, the probability that component C is in good working condition is 5/6 otherwise, it is 1/10.

The machine can only be effective when component Z is in good working condition.

Required:
(i) The probability that the machine is effective.

(ii) The probability that only one component Y or Z is in good working condition.

(iii) The probability that component Y is in good working condition given that component Z is in good working condition.
A

Solution


i) The probability that the machine is effective


Let:

X = x being in good working condition
X = x' not being in good working condition

Y = y being in good working condition
Y = y' not being in good working condition

Z = z being in good working condition
Z = z' not being in good working condition

P(X) = 7 / 10
P(x') = (3 / 10) / 1

P(Y / X) = 3 / 5

P(Y'/ X) = (2 / 5) / 1

P(Y / X') = 1 / 3

P(Y'X') = (2 / 3) / 1

P(Z / XY) = 5 / 6

P(Z' / XY) = (1 / 6) / 1

P(Z / X'Y') = 1 / 10

P(Z' / X'Y') = (9 / 10) / 1

The probability that the machine is effective

P(XYZ) = 7 / 10 x 3 / 5 x 5 / 6 = 7 / 20

(ii) The probability that only one component Y or Z is in good working condition.


(3 / 10 x 1 / 3) + (3 / 10 x 2 / 3 x 1 / 10) = 1 / 10 + 2 / 100

12 / 100 = 3 / 25

(iii) The probability that component Y is in good working condition given that component Z is in good working condition.


P(X / Z) = (3 / 5) / (5 / 6) = 3 / 5 x 6 / 5 = 0.72




QUESTION 5(b)

Q The data below represent the sales made by Pengo Traders for a period of three years:

Sales (Sh. "000,000")
Quarter
Year
2012
2013
2014
1
2.2
2.9
3.2
2
5
5.2
5.8
3
7.9
8.2
9.1
4
3.2
3.8
4.1

Required:
(i) The centred moving average trend values.

(ii) The seasonal additive indices.

(iii) The deseasonalised time series.
A

Solution


(i) The centred moving average trend values.



Year

Quarter(Q)

Sales(Y)

4QMA

4CMAT
Seasonal fluctuation
(Sales(Y) - 4CMAT)


2012







2013








2014


1
2

3

4

1

2

3

4

1

2

3
4
2.2
5

7.9

3.2

2.9

5.2

8.2

3.8

3.2

5.8

9.1
4.1


4.575

4.75

4.8

4.875

5.025

5.10

5.25

5.475

5.55





4.663

4.775

4.838

4.950

5.063

5.175

5.363

5.513






3.237

-1.575

-1.938

0.25

3.137

-1.375

-2.163

0.287





Calculating 4 center moving average trend values


Step 1


Get the average of the first four Y

4CMA
=
2.2 + 5 + 7.9 + 3.2 + 2.9

4
= 4.575


Step 2


Get the average of the next four Y

4CMA
=
5 + 7.9 + 3.2 + 2.9 + 5.2

4
= 4.75


Step 3


Get the average of the first and second 4QMA

4CMAT
=
4.575 + 4.75

2
= 4.663


Continue with this process until you find all the values

(ii) The seasonal additive indices.


Year Quarter 1 Quarter 2 Quarter 3 Quarter 4
2012
2013
2014
-
-1.9375
-2.1625
-
0.25
0.2875
3.2375
3.1375
-
-1.575
-1.375
-
Total index
Average index
Adjusted index
Round off
-4.1
-2.05
-2.038125
-2.0
0.5375
0.26875
0.2859375
0.3
6.375
3.1875
3.2046875
3.2
-2.95
-1.475
-1.4578125
-1.5
-0.1375
-0.06875
0
0


Adjusted index = average index -(-0.06875) / 4 for each quarter

iii) The deseasonalised time series


Year Quarter Sales Seasonal index Deseasonalized data
(Sales - index)
2012 1
2
3
4
2.2
5
7.9
3.2
-2.0
0.3
3.2
-1.5
4.2
4.7
4.7
4.7
2013 1
2
3
4
2.9
5.2
8.2
3.8
-2.0
0.3
3.2
-1.5
4.9
4.9
5
5.3
2014 1
2
3
4
3.2
5.8
9.1
4.1
-2.0
0.3
3.2
-1.5
5.2
5.5
5.9
5.6




QUESTION 5(c)

Q Highlight the four components of a time series.
A

Solution


Components of a Time Series:


  • Trend: The long-term movement or direction in a time series. It represents the underlying pattern that may show an increase, decrease, or remain stable over time.
  • Seasonality: The regular and predictable fluctuations in a time series that occur at specific intervals, often related to calendar time (e.g., daily, monthly, or annually).
  • Cycle: The repeating up and down movements or fluctuations in a time series that are not of fixed period, typically representing economic or business cycles.
  • Irregularity (or Residual): The random fluctuations or noise in a time series that cannot be attributed to the trend, seasonality, or cycle. It represents the unpredictable and unsystematic components.



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