Probability

The probability scale

Name: ______________________________Date: ______________Score: ______ / 20

1.
A probability is written as 9%. What is it as a decimal?
2.
What is the probability of an event that is certain to happen?
1. A1
2. B0
3. C0.5
3.
An event can have a probability of 112%.
True False
4.
A coin has landed heads five times in a row. The probability that the next flip is heads is more than 50%.
True False
5.
Put these words in order, from least likely to most likely.
Write the order (least likely first) in the boxes:
- ?likely
- ?impossible
- ?certain
- ?even chance
- ?unlikely
6.
Sort each event by how likely it is.
Write each item’s group (Impossible / Certain):
- rolling a 7 on an ordinary six-sided dice
- rolling a number less than 7 on an ordinary dice
- a coin landing on neither heads nor tails
- tomorrow following today
7.
Write 5/10 as a percentage.
1. A5%
2. B50%
8.
Team A wins with probability 72%. Team B wins with probability 6/10. Which team is more likely to win?
1. ATeam B
2. BTeam A
3. Cthey are equally likely
9.
A probability is written as 77%. What is it as a decimal?
10.
An event has a probability of 17%. Which word describes it best?
1. Aimpossible
2. Beven chance
3. Cunlikely
11.
Write the probability 13/20 as a percentage.
%
12.
A probability is written as 21%. What is it as a decimal?
13.
An event can have a probability of 125%.
True False
14.
The probability of rain tomorrow is 28%. What is the probability that it does NOT rain?
%
15.
Write 8/10 as a percentage.
1. A8%
2. B80%
3. C20%
16.
Team A wins with probability 48%. Team B wins with probability 1/10. Which team is more likely to win?
1. ATeam B
2. BTeam A
3. Cthey are equally likely
17.
The probability of rain tomorrow is 12%. What is the probability that it does NOT rain?
%
18.
Team A wins with probability 36%. Team B wins with probability 8/10. Which team is more likely to win?
1. ATeam A
2. Bthey are equally likely
3. CTeam B
19.
The probability of rain tomorrow is 89%. What is the probability that it does NOT rain?
%
20.
An event has a probability of 49%. Which word describes it best?
1. Aunlikely
2. Bimpossible
3. Ceven chance

Answer key

Probability — The probability scale

1.0.09
2.A. 1
3.False
4.False
5.impossible, unlikely, even chance, likely, certain
6.rolling a 7 on an ordinary six-sided dice = Impossible; rolling a number less than 7 on an ordinary dice = Certain; a coin landing on neither heads nor tails = Impossible; tomorrow following today = Certain
7.B. 50%
8.B. Team A
9.0.77
10.C. unlikely
11.65 %
12.0.21
13.False
14.72 %
15.B. 80%
16.B. Team A
17.88 %
18.C. Team B
19.11 %
20.A. unlikely