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University of Pretoria

Faculty of Economic and Management Sciences Department of Statistics Statistics 110 (STK110)

Semester Test 1: 29 March 2012

Time: 90 minutes Total: 55 Marks

Internal Examiners: Mrs M Coelho Ms. J Coetsee Ms. T Hine Mrs. F Reyneke Mr. G Visser External Examiner: Prof F Steffens

Instructions: Answer all questions.

Complete the multi-choice answer sheet with pencil on Side 1.

Check that your student number is filled in correctly on the multi-choice answer sheet.

Do calculations on the counter page of the question paper if necessary.

List of formulae is attached.

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Outeursreg Voorbehou

Universiteit van Pretoria Fakulteit Ekonomiese en Bestuurswetenskappe

Departement Statistiek Statistiek 110 (STK110)

Semestertoets 1: 29 Maart 2012

Tyd: 90 minute Totaal: 55 Punte

Interne eksaminatore: Me. M Coelho Me. J Coetsee Me. T Hine Me. F Reyneke Mnr. G Visser Eksterne eksaminator: Prof F Steffens

Instruksies:

Beantwoord al die vrae.

Vul die meerkeuse antwoordblad op Kant 1 met potlood in.

Kontroleer dat jou studentenommer korrek op die meerkeuse antwoordblad ingevul is.

Doen berekeninge op die teenblad van die vraestel indien nodig.

Lys van formules is aangeheg.

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Test Regulations

1. No candidate may enter the test hall later than half an hour after the test session has commenced and no candidate may leave the test hall earlier than half an hour after the test session has commenced.

2. Candidates are obliged to execute immediately all instructions given by an invigilator.

3. Candidates may not take into the test hall or have in their possession any unauthorized apparatus, books, notes or paper of whatever nature or size.

4. Once the invigilator has announced that the test has commenced, all conversation or any other form of communication between candidates must cease. During the course of the test there may be no communication of any nature between candidates.

5. No candidates may assist or attempt to assist another candidate, or obtain

assistance or obtain assistance from another candidate with regard to any information.

6. Candidates shall not act dishonestly in any respect.

7. Writing on any paper other than that supplied for test purposes is strictly prohibited.

8. Rough work may be done on the counter page of the test paper.

9. Smoking is not permitted in the test hall and candidates may not leave the test hall during the test in order to smoke outside.

10. Only in exceptional circumstances will a candidate be given permission to leave the

test hall temporarily, and then only under the supervision of an invigilator.

11. Candidates may not remove used or unused answer sheets from the test hall.

12. When the invigilator announces that the time has expired, candidates must stop writing immediately.

PLEASE NOTE: Candidates are seriously warned about contravening any of these instructions and that, if found guilty, a candidate could forfeit all credits for a whole year and also be suspended from the University (and consequently from all South African universities) for a period that could range from one year to permanent suspension.

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Toetsregulasies

1. Geen kandidaat sal later as ‘n halfuur na die aanvang van ‘n toetssessie tot die toetslokaal toegelaat word nie en geen kandidaat mag die toetslokaal vroeër as ‘n halfuur na die aanvang van die toetssessie verlaat nie.

2. Kandidate is verplig om alle opdragte van ‘n opsiener onmiddellik na te kom.

3. Kandidate mag geen ongemagtigde apparaat, boeke, aantekeninge van welke aard

ookal of enige papier hoe gering ookal, in die toetslokaal inneem nie of in hulle besit hê nie.

4. Nadat die opsiener aangekondig het dat die toets begin, moet alle gesprekke of

enige ander wyse van kommunikasie tussen studente gestaak word. Tydens die duur van toets mag daar geen gedagtewisseling van welke aard ookal tussen kandidate plaasvind nie.

5. Geen kandidaat mag ‘n ander kandidaat help of probeer help, of hulp verkry, of

probeer om hulp van ‘n ander kandidaat te verkry met betrekking tot enige inligting nie.

6. Kandidate mag hulle nie aan enige oneerlikhede skuldig maak nie.

7. Dit is ten strengste verbied om op enige ander papier te skryf as dié wat vir

toetsdoeleindes verskaf word.

8. Rofwerk mag op die teenblad van die vraestel gedoen word.

9. Binne die toetslokaal mag daar nie gerook word nie en kandidate mag nie gedurende die toets die lokaal verlaat met die doel om buitekant te rook nie.

10. Slegs in buitengewone omstandighede sal aan ‘n kandidaat toestemming verleen

word om die toets tydelik te verlaat en dan slegs onder toesig van ‘n opsiener.

11. Kandidate mag nie gebruikte of ongebruikte antwoordblaaie uit die toetslokaal uit neem nie.

12. Sodra die opsiener aankondig dat die tyd verstreke is, moet kandidate onmiddellik

ophou skryf.

LET WEL: Kandidate word ernstig gewaarsku teen oortreding van hierdie instruksies en daarop gewys dat by skuldigbevinding ‘n kandidaat alle krediet vir ‘n hele jaar se werk verbeur en daarbenewens uit die Universiteit (en gevolglik alle Suid-Afrikaanse universitêre inrigtings) geskors kan word vir ‘n tydperk wat kan wissel van een jaar tot permanente skorsing.

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Questions 1 to 5 are based on the following information:

Forty students were asked how many hours they spend on Facebook per day and the results are summarised in the following stem-and-leaf display.

Leaf unit = 0.1

3 1 2 3 3 7 9

4 0 1 2 3 3 5 6 8 8 9

5 1 2 2 2 4 5 8

6 1 3 5 6

7 3 4 5 5

8 0 3 9

9 3

10 2 3

11 8

12 3 7

Given: 4.3 and 7.5

Question 1 The type of data and measurement scale are:

(A) Quantitative, interval (B) Quantitative, ratio

(C) Qualitative, nominal (D) Qualitative, ordinal

(E) Qualitative, ratio

(1) Question 2 The median is:

(A) 5.3 (B) 4.3

(C) 5.4 (D) 5.2

(E) 4.2

(1) Question 3

The thirty third percentile, , is:

(A) 8.3 (B) 14

(C) 5.1 (D) 4.8

(E) 13

(2) Question 4 The shape of the data set is:

(A) symmetric (B) skewed to the left

(C) skewed to the right (D) multimodal

(E) bimodal

(1)

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Vrae 1 tot 5 is gebaseer op die volgende inligting: Veertig studente is gevra hoeveel ure hulle per dag op Facebook spandeer en die resultate is opgesom in die volgende stingel-en-blaarvoorstelling.

Blaareenheid = 0.1

3 1 2 3 3 7 9

4 0 1 2 3 3 5 6 8 8 9

5 1 2 2 2 4 5 8

6 1 3 5 6

7 3 4 5 5

8 0 3 9

9 3

10 2 3

11 8

12 3 7

Gegee: 4.3 en 7.5

Vraag 1 Die datatipe en metingskaal is:

(A) Kwantitatief, interval (B) Kwantitatief, verhouding

(C) Kwalitatief, nominaal (D) Kwalitatief, ordinaal

(E) Kwalitatief, verhouding

(1) Vraag 2 Die mediaan is:

(A) 5.3 (B) 4.3

(C) 5.4 (D) 5.2

(E) 4.2

(1) Vraag 3

Die drie-en-dertigste persentiel, , is:

(A) 8.3 (B) 14

(C) 5.1 (D) 4.8

(E) 13

(2) Vraag 4 Die vorm van die datastel is:

(A) simmetries (B) skeef na links

(C) skeef na regs (D) multimodaal

(E) bimodaal

(1)

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Question 5 For a box-plot, the upper limit is:

(A) 2.7 (B) 12.3

(C) 9.1 (D) 11.8

(E) 7.5

(2)

Questions 6 to 8 are based on the following information: 200 students were asked to indicate their favourite internet activity and the results are summarised in the following bar graph:

Question 6 The scale of measurement is:

(A) Nominal (B) Ordinal

(C) Interval (D)Ratio

(E) Discrete

(1)

Question 7

The mode is:

(A) 55 (B) 30

(C) Dating, YouTube and Skype (D) 20

(E) Facebook

(1)

Question 8

The proportion of students, whose favourite internet activity is Twitter, is:

(A) 0.15 (B) 15

(C) 0.85 (D) 0.075

(E) 0.925

(1)

0

10

20

30

40

50

60

15 20

55

30 30

20

30

Fre

qu

en

cy

Internet activity

Bar graph of favourite internet activity

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Vraag 5 Vir ‘n houer-en-punt voorstelling, is die boonste limiet:

(A) 2.7 (B) 12.3

(C) 9.1 (D) 11.8

(E) 7.5

(2)

Vrae 6 tot 8 is gebaseer op die volgende inligting: 200 studente is gevra wat hulle gunsteling internetaktiwiteit is en die resultate is opgesom in die volgende staafdiagram:

Vraag 6 Die metingskaal is:

(A) Nominal (B) Ordinal

(C) Interval (D)Ratio

(E) Discrete

(1)

Vraag 7

Die modus is:

(A) 55 (B) 30

(C) Dating, YouTube en Skype (D) 20

(E) Facebook

(1)

Vraag 8

Die verhouding van studente wie se gunsteling internetaktiwiteit Twitter is, is:

(A) 0.15 (B) 15

(C) 0.85 (D) 0.075

(E) 0.925

(1)

0

10

20

30

40

50

60

15 20

55

30 30

20

30

Fre

kwe

nsi

e

Internetaktiwiteit

Staafdiagram van gunsteling Internetaktiwiteit

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Questions 9 to 11 are based on the following information: A random sample of 75 Facebook users was selected and the number of friends each user had was recorded and summarised in the following Excel spread sheet: Formula worksheet:

Value worksheet:

Question 9 An estimate of a typical value for the fourth class interval is:

(A) 15 (B) 175.5

(C) 151 (D) 200

(E) 53.78

(1) Question 10 The value of the sample mean is:

(A) 168.17 (B) 2 522.5

(C) 150.00 (D) 15

(E) 12 612.5

(1) Question 11 The value of the sample variance is:

(A) 454.70 (B) 460.84

(C) 6820.44 (D) 4446.22

(E) 4506.31

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(2) Vrae 9 tot 11 is gebaseer op die volgende inligting: ‘n Ewekansige steekproef van 75 Facebook gebruikers is gekies en die aantal vriende wat elke gebruiker het, is aangeteken en opgesom in die volgende Excel spreiblad: Formule werkblad:

Waarde werkblad:

Vraag 9 ‘n Beraming van ‘n tipiese waarde in die vierde klasinterval is:

(A) 15 (B) 175.5

(C) 151 (D) 200

(E) 53.78

(1) Vraag 10 Die waarde van die steekproefgemiddelde is:

(A) 168.17 (B) 2 522.5

(C) 150.00 (D) 15

(E) 12 612.5

(1) Vraag 11 Die waarde van die steekproefvariansie is:

(A) 454.70 (B) 460.84

(C) 6820.44 (D) 4446.22

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(E) 4506.31

(2)

Questions 12 to 16 are based on the following information:

A company wanted to determine how much time employees spend updating their statuses

on Facebook and Twitter per month during office hours. The company recorded the time

(in hours) spent on these social media platforms of 80 employees and the results are

respresented in the following ogive:

Question 12 This data is an example of:

(A) Cross sectional data (B) Time series data

(1) Question 13 The percentage of employees who spend more than 30 hours on Facebook and Twitter during office hours is approximately:

(A) 20% (B) 25%

(C) 80% (D) 70%

(E) 75%

(2) Question 14 The relative frequency of the modal class interval is approximately:

(A) 0.35 (B) 0.44

(C) 0.88 (D) 0.70

(E) 0.56

(2) Question 15 The interquartile range is approximately:

0

10

20

30

40

50

60

70

80

10 20 30 40 50 60

Cu

mu

lati

ve f

req

ue

ncy

Time (in hours) spent on Facebook and Twitter

Ogive of time spent on Social media during office hours

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(A) 40 (B) 75

(C) 20 (D) 17

(E) 5

(2) Vrae 12 tot 16 is gebaseer op die volgende inligting: ‘n Maatskappy wil vasstel hoeveel tyd werknemers spandeer om hulle Facebook en Twitter statusse per maand op te dateer gedurende werksure. Die maatskappy het die tyd (in ure) wat spandeer word op sosiale media platforms van 80 werknemers aangeteken en die resultate word voorgestel in die volgende ogief:

‚ Vraag 12 Die data is ‘n voorbeeld van:

(A) Tydsnitdata (B) Tydreeksdata

(1) Vraag 13 Die persentasie werknemers wat meer as 30 ure op Facebook en Twitter gedurende werksure spandeer is benaderd:

(A) 20% (B) 25%

(C) 80% (D) 70%

(E) 75%

(2) Vraag 14 Die relatiewe frekwensie van die modale interval is benaderd:

(A) 0.35 (B) 0.44

(C) 0.88 (D) 0.70

(E) 0.56

(2) Vraag 15

0

10

20

30

40

50

60

70

80

10 20 30 40 50 60

Ku

mu

lati

ew

e f

rekw

en

sie

Tyd (in ure) spandeer op Facebook en Twitter

Ogief van tyd spandeer op Sosiale media gedurende werksure

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Die interkwartielvariasiewydte is benaderd:

(A) 40 (B) 75

(C) 20 (D) 17

(E) 5

(2)

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Question 16

Only 20% of the employees spend more than hours on Facebook and Twitter during office hours.

(A) 60 (B) 49

(C) 30 (D) 27

(E) 16

(2)

Questions 17 to 21 are based on the following information:

Let The amount of money (in Rand) people spend per month on new e-books for their Kindles.

has a symmetric bell-shaped distribution with a mean of R350 and variance of R49. Question 17 The percentage of people who spend between R336 and R357 is approximately:

(A) 95 (B) 68

(C) 45 (D) 55

(E) 81.5

(2) Question 18 The percentage of people who spend less than R364 is approximately:

(A) 68 (B) 97.5

(C) 70 (D) 75

(E) 95

(2) Question 19

The eighty fourth percentile, , is approximately:

(A) R434 (B) R399

(C) R448 (D) R357

(E) R364

(1) Question 20 An amount (in Rand) lower than may be regarded as an outlier. (Choose the largest value that satisfies this condition.)

(A) 301 (B) 371

(C) 329 (D) 497

(E) 203

(1) Question 21

A value( ) in the data set has a . The corresponding value of is:

(A) 347.9 (B) 335.3

(C) 350.3 (D) 349.7

(E) 347.0

(1)

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Vraag 16 Slegs 20% van die werknemers spandeer meer as ure op Facebook en Twitter gedurende werksure.

(A) 60 (B) 49

(C) 30 (D) 27

(E) 16

(2)

Vraag 17 tot 21 is gebaseer op die volgende inligting:

Laat Die bedrag geld (in Rand) wat mense per maand spandeer om nuwe e-boeke vir hulle Kindles te koop.

het ‘n simmetriese klokvormige verdeling met ‘n gemiddelde van R350 en variansie van R49. Vraag 17 Die persentasie mense wat tussen R336 en R357 spandeer is benaderd:

(A) 95 (B) 68

(C) 45 (D) 55

(E) 81.5

(2) Vraag 18 Die persentasie mense wat minder as R364 spandeer is benaderd:

(A) 68 (B) 97.5

(C) 70 (D) 75

(E) 95

(2) Vraag 19

Die vier-en-tagtigste persentiel, , is benaderd:

(A) R434 (B) R399

(C) R448 (D) R357

(E) R364

(1) Vraag 20 ‘n Bedrag (in Rand) minder as kan beskou word as ‘n uitskieter. (Kies die grootste waarde wat aan die voorwaarde voldoen.)

(A) 301 (B) 371

(C) 329 (D) 497

(E) 203

(1) Vraag 21

‘n Waarde( ) in die datastel het ‘n . Die ooreenkomstige waarde van is:

(A) 347.9 (B) 335.3

(C) 350.3 (D) 349.7

(E) 347.0

(1)

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Questions 22 to 25 are based on the following information:

The relationship between the time spent on social media during office hours, , (in hours

per week) and employee productivity, ,(in percentage) is investigated in the following Excel spread sheet: Formula worksheet:

Value worksheet:

Question 22 The value of sample standard deviation of the employee productivity ( ) is:

(A) 835.71 (B) 27.04

(C) 731.25 (D) 3.70

(E) 28.91

(2)

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Vrae 22 tot 25 is gebaseer op die volgende inligting:

Die verwantskap tussen die tyd spandeer op sosiale media gedurende werksure, , (in ure

per week) en werknemersproduktiwiteit, ,(in persentasie) is ondersoek in die volgende Excel spreiblad: Formule werkblad:

Waarde werkblad:

Vraag 22 Die waarde van die steekproefstandaardafwyking van die werknemersproduktiwiteit ( ) is:

(A) 835.71 (B) 27.04

(C) 731.25 (D) 3.70

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(E) 28.91

(2)

Question 23

The value of the sample covariance is:

(A) 835.71 (B) -101.43

(C) -88.75 (D) 13.71

(E) 0

(1)

Question 24 The sample correlation coefficient of -0.9474 suggests that:

(A) the variation in is larger than the variation in . (B) the variation in is larger than the variation in . (C) there is no linear relationship between and .

(D) there is a strong negative linear relationship between and (E) there is a strong negative nonlinear relationship between and

(1)

Question 25 If the variation in the time spent on social media (in hours per week), relative to the average time spent, must be compared to the employee productivity (in percentage), relative to the average employee productivity, it is necessary to look at the value(s) of the: (A) range (B) covariance (C) interquartile range (D) coefficient of variation (E) variance

(1)

Questions 26 and 27 are based on the following information: A random sample of ten students was asked whether they use Facebook, of which the only acceptable answers were “Yes” or “No”. It was found that the probability that a student will answer “Yes” to this question is 0.75. Question 26 The total number of experimental outcomes is:

(A) 45 (B) 20

(C) 90 (D) 100

(E) 1024

(2) Question 27 The probability that the first student will answer “No” and the rest will answer “Yes” is:

(A) 0.8125 (B) 0.0188

(C) 0.3333 (D) 0.1875

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(E) 0.6667

(2) Vraag 23 Die waarde van die steekproefkovariansie is:

(A) 835.71 (B) -101.43

(C) -88.75 (D) 13.71

(E) 0

(1)

Vraag 24 Die steekproefkorrelasiekoëffisiënt van -0.9474 dui aan dat :

(A) die variasie in groter is as die variasie in . (B) die variasie in groter is as die variasie in .

(C) daar geen lineêre verwantskap tussen en is nie. (D) daar ‘n sterk negatiewe lineêre verwantskap tussen en is. (E) daar ‘n sterk negatiewe nie-lineêre verwantskap tussen en is.

(1)

Vraag 25 Indien die variasie in the tyd spandeer op sosiale media (in ure per week), relatief tot die gemiddelde tyd spandeer, vergelyk moet word met die variasie in die werknemersproduktiwiteit (in persentasie), relatief tot die gemiddelde werknemersproduktiwiteit, is dit nodig om na die waarde(s) te kyk van die: (A) variasiewydte (B) kovariansie (C) interkwartielvariasiewydte (D) variasiekoëffisiënt (E) variansie

(1)

Vrae 26 en 27 is gebaseer op die volgende inligting: ‘n Ewekansige steekproef van 10 studente is gevra of hulle Facebook gebruik, waar die aanvaarbare antwoorde “Ja” or “Nee” was. Dit is gevind dat die waarskynlikheid dat die student “Ja” sal sê, 0.75 is. Vraag 26 Die totale aantal eksperimentele uitkomste is:

(A) 45 (B) 20

(C) 90 (D) 100

(E) 1024

(2) Vraag 27 Die waarskynlikheid dat die eerste student sal “Nee” antwoord en die res “Ja” sal antwoord is:

(A) 0.8125 (B) 0.0188

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(C) 0.3333 (D) 0.1875

(E) 0.6667

(2)

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Questions 28 to 31 are based on the following information: In order to investigate the relationship between Social media preference and gender a random sample of 400 people were selected and the results are summarised in the following contingency table:

Social media preference

Gender

Male Female Total

Facebook 80 200 280

Twitter 20 100 120

Total 100 300 400

Define the events as follows:

Randomly selected person prefers Facebook

Randomly selected person is a man

Question 28 The probability that a randomly selected person prefers Facebook is:

(A) 0.2 (B) 0.286

(C) 0.7 (D) 0.667

(E) 0.8

(1)

Question 29

( )

(A) 0.8 (B) 0.667

(C) 0.25 (D) 0.286

(E) 0.2

(1) Question 30

( ) (A) 0.45 (B) 0.95

(C) 0.5 (D) 0.05

(E) 0.55

(1) Question 31

Events and are:

(A) statistically independent, because ( ) ( ) (B) statistically dependent, because ( ) ( ) (C) statistically independent, because ( ) ( ) (D) statistically dependent, because ( ) ( ) (E) statistically independent, because ( ) ( )

(2)

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Vrae 28 tot 31 is gebaseer op die volgende inligting: Om ondersoek in te stel na die verwantskap tussen sosiale media voorkeure en geslag is ‘n ewekansige steekproef van 400 mense gekies en die resultate is opgesom in die volgende gebeurlikheidstabel:

Sosiale media voorkeur

Geslag

Manlik Vroulik Totaal

Facebook 80 200 280

Twitter 20 100 120

Totaal 100 300 400

Definieer die gebeurtenisse soos volg:

Ewekansig gekose persoon verkies Facebook

Ewekansig gekose persoon is ‘n man

Vraag 28 Die waarskynlikheid dat ‘n ewekansig gekose persoon Facebook verkies is:

(A) 0.2 (B) 0.286

(C) 0.7 (D) 0.667

(E) 0.8

(1)

Vraag 29

( )

(A) 0.8 (B) 0.667

(C) 0.25 (D) 0.286

(E) 0.2

(1) Vraag 30

( ) (A) 0.45 (B) 0.95

(C) 0.5 (D) 0.05

(E) 0.55

(1) Vraag 31

Gebeurtenisse en is:

(A) statisties onafhanklik, want ( ) ( ) (B) statisties afhanklik, want ( ) ( ) (C) statisties onafhanklik, want ( ) ( ) (D) statisties afhanklik, want ( ) ( ) (E) statisties onafhanklik, want ( ) ( )

(2)

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Questions 32 to 35 are based on the following information: Out of a random sample of 100 people it was found that the probability that a person used Facebook is 0.65 and the probability that a person uses Twitter is 0.35. It was also observed that the probability that a person uses both Facebook and Twitter is 0.25.

Define the events: Person uses Facebook

Person uses Twitter Question 32 The method used to calculate the probabilities is the: (A) classical method

(B) coefficient of variation

(C) relative frequency method

(D) empirical rule

(E) subjective method

(1) Question 33 The probability that a randomly selected person uses Facebook, given that he/she uses Twitter is:

(A) 0.3846 (B) 0.2500

(C) 0.6000 (D) 0.2275

(E) 0.7143

(2) Question 34 The probability that a randomly selected person uses Facebook or Twitter is:

(A) 0.7500 (B) 1.0000

(C) 0.0875 (D) 0.2275

(E) 0.6000

(2) Question 35 The events are not mutually exclusive, because: (A) ( ) ( )

(B) ( )

(C) ( ) ( ) ( )

(D) ( )

(E) ( ) ( )

(1)

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Vrae 32 tot 35 is gebaseer op die volgende inligting: Uit ‘n ewekansige steekproef van 100 mense is dit gevind dat die waarskynlikheid dat ‘n persoon Facebook gebruik 0.65 is en die waarskynlikheid dat ‘n persoon Twitter gebruik 0.35 is. Dit is ook waargeneem dat die waarskynlikheid dat ‘n persoon beide Facebook en Twitter gebruik 0.25 is.

Definieer die volgende gebeurtenisse: Persoon gebruik Facebook

Persoon gebruik Twitter Vraag 32 Die metode wat gebruik is om waarskynlikhede te bereken is die: (A) klassieke metode

(B) variasiekoëffisiënt

(C) relatiewe frekwensiemetode

(D) empiriese reël

(E) subjektiewe metode

(1) Vraag 33 Die waarskynlikheid dat ‘n ewekansig gekose persoon Facebook gebruik, gegee dat hy/sy Twitter gebruik, is:

(A) 0.3846 (B) 0.2500

(C) 0.6000 (D) 0.2275

(E) 0.7143

(2) Vraag 34 Die waarskynlikheid dat ‘n ewekansig gekose persoon Facebook of Twitter gebruik is:

(A) 0.7500 (B) 1.0000

(C) 0.0875 (D) 0.2275

(E) 0.6000

(2) Vraag 35 Die gebeurtenisse is nie onderling uitsluitend nie, want: (A) ( ) ( )

(B) ( )

(C) ( ) ( ) ( )

(D) ( )

(E) ( ) ( )

(1)

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Questions 36 to 38 are based on the following information: The probability distribution of

number of times a person updates his/her Facebook status per day

is displayed in the following table:

Number of daily Facebook status updates

Probability

0 0.45

1 0.25

2 0.15

3 0.10

4 0.05

Question 36

The probability distribution of is:

(A) Bimodal (B) Continuous

(C) Multimodal (D) Discrete

(E) Uniform

(1)

Question 37 The expected number of Facebook status updates per day is:

(A) 0 (B) 2

(C) 1 (D) 1.5

(E) 1.05

(2)

Question 38 The probability that a person updates his/her Facebook status more than once a day is:

(A) 0.30 (B) 0.55

(C) 0.25 (D) 0.70

(E) 0.45

(2)

27

Vrae 36 tot 38 is gebaseer op die volgende inligting: Die waarskynlikheidsverdeling van

aantal kere wat ‘n persoon sy/haar Facebook status per dag opdateer

is voorgestel in die volgende tabel:

Aantal daaglikse Facebook statusopdaterings

Waarskynlikheid

0 0.45

1 0.25

2 0.15

3 0.10

4 0.05

Vraag 36

Die waarskynlikheidsverdeling van is:

(A) Bimodaal (B) Kontinu

(C) Multimodaal (D) Diskreet

(E) Uniform

(1)

Vraag 37 Die verwagte aantal Facebook statusopdaterings per dag is:

(A) 0 (B) 2

(C) 1 (D) 1.5

(E) 1.05

(2)

Vraag 38 Die waarskynlikheid dat ‘n persoon sy/haar Facebook status meer as eenkeer per dag opdateer is:

(A) 0.30 (B) 0.55

(C) 0.25 (D) 0.70

(E) 0.45

(2)

28

Formulae STK110 (Page 1 of 1)

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