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Woldgate College Maths Department
Name:
Year 10 Homework 5H (Probability)
Date Due:
Use a calculator!
Objectives:
• Use a number to represent a probability.
• Find and estimate probabilities.
• Add and multiply probabilities.
Grade
D
1. A Letter is chosen at random from the word PROBABILITY.
Write down the probability that it will be:
a) B
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Grade
D
b) Y
(1 Mark) =
c) R or I
(1 Mark) =
d) a vowel
(1 Mark) =
e) G
(1 Mark) =
(1 Mark)
2. A bag contains counter which are red, green, yellow or blue. The table shows each of the
probabilities that a counter will be taken at random from the bag.
a) A counter is taken from the bag. Work out the probability that the counter will be yellow.
P(Y) =
(1 Mark)
b) The bag contains 200 counters. Work out the number of red counters in the bag.
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Grade
D
(1 Mark)
3. The table gives the number of boys and the number of girls in a primary school and whether
they are left-handed or right-handed.
a) Complete the table.
(2 Marks)
b) One of these children is chosen at random. Use the information in your table to work out
the probability that the child will be:
i) A boy.
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ii) Left-handed.
(1 Mark)
=
iii) A right-handed girl.
(1 Mark)
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(1 Mark)
Grade
C
4. Two ordinary dice are rolled one red and the other one blue the scores are then added
together. Draw a sample space diagram to show all possible outcomes.
(3 Marks)
Work out the probability of getting each of the following outcomes.
i) 2
ii) 5
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(1 Mark)
iv) the same number on each
dice.
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Grade
B
iii) 10 or more
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(1 Mark)
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v) a number on the blue dice exactly 2 more than the number
on the red dice.
(1 Mark)
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(2 Marks)
6. A bag contains red balls, blue balls and green balls in the ratio 2:3:4. A ball is taken at
random from the bag. Work out the probability that the ball will be:
a) Red.
b) Not red.
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Grade
A
(1 Mark)
5. A and B are two mutually exclusive events. P(A) = 0.45 and P(A or B) = 0.8.
Work out the value of P(B).
P(B) =
Grade
B
(1 Mark)
(1 Mark)
c) Not green.
=
(1 Mark)
=
(1 Mark)
7. For two mutually exclusive events A and B, P(B) = 0.3 and P(A or B) = 0.7. Work out P(not A).
P(not A) =
(2 Marks)
8. Simon plays one game of tennis and one game of snooker. The probability that Simon will
win at tennis is ¾ . The probability that Simon will win at snooker is 1/3.
a) Complete the probability tree diagram.
(2 Marks)
b) Work out the probability that Simon
wins both games.
(2 Marks)
c) Work out the probability that Simon
will win only one game.
(3 Marks)
Grade
A*
9. There are 4 orange sweets, 2 red sweets and 3 green sweets in a bag. Sue takes a sweet
at random. She eats the sweet. She then takes another sweet at random.
Work out the probability that the sweets are different colours.
Please show all of your working out.
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Total:
Target:
Purple pen box
/38
Percentage:
(4 Marks)
%