ADM2623 FR01A
Quiz 3 (Oct 21, 2015)
Name
Student ID
Instruction:
1. Please justify your answers by providing the methods and/or the procedures for your final
results. You will not get any credit for a single answer without proper process (except
multiple choice questions).
2. There are two questions in total.
3. Total mark is 7
Problem 1 (3 marks)
1. (1 point) What is a random experiment?
ANS: A process that satisfies the following properties:
1.
2.
3.
4.
the process can be repeated as many trials as you want
the outcome of any trial is uncertain
well-defined set of possible outcomes
each outcome has a probability associated with it
2. (1 point) A study by Sabo & Veliz (2008) surveyed 2,132 American children about their
participation in organized and team sports. In the sample, 50.7% were boys and 49.3%
were girls. Of the boys, 73% currently participate in sports. Of the girls, 63% currently
participate in sports. Gender and sports participation are NOT independent. If you
randomly select an individual from this sample, what is the probability that you would
select a girl who currently participates in sports?
ANS: P(girl∩sports)=P(girl)×P(sports∣girl)=.493×.63=.311
3. (1 point) In Canada, 83% of citizens can speak English, 31% of citizens can speak
French, 18% are English-French Bilingual, and there are also some citizens who speak
neither English nor French. What is the probability that a randomly selected citizen of
Canada will speak either English or French?
ANS: P(English∪French)=P(English)+P(French)−P(English∩French)=.83+.31−.18=.96
Problem 2 (4 marks) The Canadian Coffee Producers Association reports the following table
below on age and the amount of coffee consumed in a month.
Coffee Consumption
Low
Moderate
High
Under 21 years
36
32
32
100
21 - 40 years
35
20
45
100
Over 40 years
20
55
25
100
91
107
102
300
(1) (1 mark) If one is randomly chosen, what is the probability that the person is under 21
and prefers to consume low amount of coffee?
ANS: 36/300
(2) (1 mark) If one is randomly chosen from people over 40, what is the probability that the
person prefers to drink moderate or high amount of coffee?
ANS: (55+25)/100=80/100
(3) (1 mark) If one is randomly chosen, what is the probability that the person does not
prefer to drink high amount of coffee?
ANS: 1-102/300=198/300
(4) (1 mark) If one is randomly chosen, what is the probability that the person prefers to
drink high amount of coffee or over 40?
ANS: (102+100-25) /300
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