Probability Assignment
1.
During a recent survey of ethnic backgrounds of 1000 people in a large city, 513
were Canadian, 148 were French, 72 were African and 56 were Asian and the
remainder were from other groups. Calculate the probability that a person, selected
at random from the population has:
a.
A Canadian background?
Probability (Canadian) = Number of Favorable Outcomes/Total Number of Possible
Outcomes
Probability (Canadian) = 513/1000
Probability (Canadian) = 0.513
Therefore, the probability that a person, selected at random from population that has a
Canadian Background is 0.513
b.
An African background?
Probability (African) = Number of Favorable Outcomes/Total Number of Possible
Outcomes
Probability (African) = 72/1000
Probability (African) = 0.072
Therefore, the probability that a person, selected at random from population that has
an African background is 0.072
c.
An “other” background?
1000 – (513 + 148 +72 + 56) = 1000
1000 – 789 = 211
There are 211 people within the “other” groups in 1000 people in a large city.
Probability (Other) = Number of Favorable Outcomes/Total Number of Possible
Outcomes
Probability (Other) = 211/1000
Probability (Other) = 0.211
Therefore, the probability that a person, selected at random from a population that has
an “other” background is 0.211
2.
A spinner is divided into three equally sized regions as shown. The spinner is spun
twice. For each probability you determine, express your answer as a fraction,
decimal and percent.
a.
What is the probability of spinning A on the first spin?
Probability = Number of Favorable Outcomes/Total Number of Possible Outcomes
Probability = 1/3
Probability = 0.3333
Probability = 0.3333 x 1000
Probability = 33.33%
Therefore, the probability is 1/3 in fraction form, 0.3333 in decimal form, and 33.33% in
percent.

b.
Draw a tree diagram to represent the sample space for both spins.
Spin 1
Spin 2
Outcome
A
A,A
A
B
A,B
B
A,B
A
B,A
B
B
B,B
B
B,B
A
B,A
B
B
B,B
B
B,B
c.
What is the probability of spinning A followed by B?
Probability = Number of Favorable Outcomes/Total Number of Possible Outcomes
Probability (A then B) = 2/9
Probability (A then B) = 0.2222
Probability (A then B) = 0.2222 x 1000
Probability (A then B) = 22.2%
Therefore, the probability is 2/9 in fraction form, 0.2222 in decimal form and 22.2% in
percentage form.
d.
What is the probability of getting the same letter on both spins?
Probability (Both spins) = Number of favorable outcomes/Total Number of Possible
Outcomes + Number of Favorable Outcomes/Total Number of Possible Outcomes
Probability (Both spins) = 1/9 + 4/9
Probability (Both spins) = 5/9
Probability (Both spins) = 0.5555 x 100
Probability (Both spins) = 55.5%
Therefore, the probability that the same letter on both spins is 5/9 in fraction form, 0.5555
in decimal form, and 55.5% in percentage form.

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- Summer '17
- Statistics, Remainder, Normal Distribution, Probability, Probability theory, Cumulative distribution function, G B G B G B