Page 153 - MAT KS3 Y8 Cambridge CheckPoint

15.2 Equally likely outcomes

4 Harsha chooses a number at random from this grid.
Find the probability that the number she chooses is: 1 2 3 4 5 6 7 8
a 27 b in the bottom row 9 10 11 12 13 14 15 16
c in the first column d not in the last two columns.
Harsha chooses another number at random from the 17 18 19 20 21 22 23 24
top two rows.
Find the probability that her number is: 25 26 27 28 29 30 31 32
e less than 10 f more than 10 33 34 35 36 37 38 39 40
g not 10 h more than 20.
5 This is a calendar for April in one year.

Monday Tuesday Wednesday Thursday Friday Saturday Sunday
1 2 3 4 5
6 7 8 9 10 11 12
13 14 15 16 17 18 19
20 21 22 23 24 25 26
27 28 29 30
Anders chooses a day at random. Find the probability that the day he chooses is:
a a Monday b not a Monday c 16 April d not 16 April e a Thursday or a Friday.
6 Zalika chooses one day of the year 2015 at random.
a What is the probability that it is: i 5 August ii not 5 August iii in August iv not in August?
b Suppose she chose a day in 2016 instead of 2015. Which probabilities in part a would be greater
now?

7 A computer generates a single-digit random number. It could be any number from 0 to 9.
Find the probability that it is:
a 0 b not 0 c a multiple of 3 d 3.5 e less than 7.

8 A computer generates a two-digit number random number. It can be any number from 00 to 99.
Find the probability that it:
a is 99 b is not 99 c has no 9s in it d has at least one 9 in it.

9 When Razi throws two coins there are four equally likely outcomes.
H = head
H H H T T H T T
T = tail

a How many of these four outcomes will give:
i two heads ii one head and one tail iii two tails?
b If two coins are thrown, what is the probability of getting:
i two heads ii one head and one tail iii two tails?
10 Sasha tosses three coins together.
a Explain why there are eight equally likely outcomes.
b Find the probability that there will be:
i three heads ii three tails iii two heads and one tail iv two tails and one head.

15 Probability 151