Download 7D SA test prob.v1

IB1 Math SL
SA 7D.v1 Test: Probability
Name________________________
Baier
Francis
Martin-Bauer
Show all work to receive full marks. Unless otherwise stated, all numerical answers should be
given exactly or correct to three significant figures.
1. [Maximum mark: 10]
Chris wishes to order a pizza from a discount shop which has a large number of pizza varieties. The pizzas
are randomly chosen and delivered by the company.
The probability that a thin-crust pizza is sent is 0.4.
The probability that pepperoni pizza is sent is 0.3.
The probability that a pizza is thin-crust or pepperoni is 0.6.
(a) Find the probability that the pizza received by Chris is not a thin-crust pepperoni.
[6]
(b) Draw a labelled Venn diagram to represent the problem. Include the probabilities of each region in
the diagram.
[4]
2. [Maximum mark: 7]
Let A and B be independent events, where P(A)  0.4 and P(B)  0.3 .
(a) Find P(AB) .
[2]
(b) Find P(AB) .
[2]
(c) (i) On the following Venn diagram, shade the
region that represents A’B .
(ii) Find P(A’B) .
[3]
3. [Maximum mark: 15]
At a large school, students are required to learn at least one language, German or Dutch. It is known that
75% of the students learn German, and 40% learn Dutch.
(a) Find the percentage of students who learn both German and Dutch.
[2 marks]
(b) Find the percentage of students who learn German, but not Dutch.
[2 marks]
At this school, 52 % of the students are girls, and 85 % of the girls learn German.
(c) A student is chosen at random. Let G be the event that the student is a girl, and let K be the
event that the student learns German.
(i)
Find P(G∩K) .
(ii) Show that G and S are not independent.
[5 marks]
(d) A boy is chosen at random. Find the probability that he learns German.
[6 marks]
4. [Maximum mark: 14]
Bill and Andrea play two games of tennis. The probability that Bill wins the first game is 4/5. If Bill wins the
first game, the probability that he wins the second game is 5/6. If Bill loses the first game, the probability
that he wins the second game is 2/3.
(a) Complete the following tree diagram.
[3]
(b) Find the probability that Bill wins the first game and Andrea wins the second game.
[2]
(c) Find the probability that Bill wins at least one game.
[4]
(d) Given that Bill wins at least one game, find the probability that he wins both games.
[5]
5. [Maximum mark: 6]
The following table shows the probability distribution of a discrete random variable X .
x
0
2
5
9
P(X = x)
0.3
k
2k
0.1
(a) Find the value of k .
[3 marks]
(b) Find E(X) .
[3 marks]
6. [Maximum mark: 10]
A factory makes lamps. The probability that a lamp is defective is 0.05. A random sample of 30 lamps is
tested.
(a) Find the probability that there is at least one defective lamp in the sample.
[4 marks]
(b) Given that there is at least one defective lamp in the sample, find the probability that there are at
most two defective lamps.
[4 marks]
(c) The factory ships 900 lamps in a month. How many defective lamps do they expect to send out
the door?
[2 marks]
Academic Honesty Pledge
Please re-write the following statement in your handwriting in the space provided below and endorse with a
signature.
“On my honor, I have neither given nor received any aid on this examination.”
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