Download Probability 2 - Wey Valley School

The Wey Valley School & Sports College
Mathematics Home Study
Page 1
PROBABILITY OF ONE EVENT
Give your answers to the following as fractions. Where possible,
simplify your fractions to their lowest terms.
UNIT: PROBABILITY
1. A packet contains 15 orange sweets and 10 lemon sweets. One
sweet is taken from the packet at random. What is the
probability that the sweet is:
(a) orange
(b) lemon?
Support work: Question 1 on each page
Core work: Question 2 on each page
Extension work: Question 3 on each page
HELP!
Probability is usually written as a fraction where the
top number is the number of successful outcomes and
the bottom number if the total number of outcomes e.g
the probability of choosing a spade from a deck of
13 1
 because 13 of the cards are spades out
cards is
52 4
of 52 cards altogether – the same as one in every four.
Page 2
PROBABILITY OF TWO EVENTS
1. The table shows all the
possible outcomes when two
fair dice are thrown and
their scores are added
together:
1
2
3
4
5
6
1
2
3
4
5
6
7
Determine the probability
that the total score on the two dice is:
(a) 5
(b) 7
(c) an even number
2
3
4
5
6
7
8
3
4
5
6
7
8
9
4
5
6
7
8
9
10
5
6
7
8
9
10
11
6
7
8
9
10
11
12
(d) a square number
2. A calculator can be used to produce random digits between 1
& 9. Pairs of random digits are added together to give a total
score.
(a) Draw up a table to show all the possible outcomes
(b) Use your table to determine the probability that the total
score is:
(i) 10 (ii) 8 (iii) less than 15 (iv) greater than 9
3. In a jar there are red and blue sweets.
(a) Draw a tree diagram to show all the possible outcomes
when two sweets are taken out of the jar
There are 3 red sweets and 7 blue sweets. Billy takes a sweet
from the jar, eats it and then takes another.
(b) Write the probabilities on the branches of your tree diagram
(c) What is the probability that the two sweets Billy chooses
are the same colour?
2. 20 balls are each marked with a different number from 1 to 20
and then placed in a bag. One ball is taken at random from the
bag. What is the probability that the number on the ball is:
(a) 17
(b) an even number
(c) a multiple of 3
(d) less than 2 (not including 2)
(e) greater than 2 (not including 2)
(f) a prime number?
3. A card is taken at random from a standard 52-card pack of
playing cards. What is the probability that the card is:
(a) a seven
(b) a Diamond
(c) not a Spade
(d) a red King
(e) a King, Queen or Jack
(f) a black Jack?