 # Opposite Probabilities

In this worksheet, students calculate the probability of events not happening. Key stage:  KS 3

Curriculum topic:   Probability

Curriculum subtopic:   Understand Probability Outcomes

Difficulty level:   ### QUESTION 1 of 10

If the probability of something happening is x, then the probability of it not happening is 1 - x.

Example

If the probability that it will rain is 3/8, then the probability that it will not rain is 1 - 3/8 = 5/8

Example The probability of the spinner landing on yellow is 3/8.

The probability of the spinner not landing on yellow is 1 - 3/8 = 5/8 The probability of the spinner landing on red is 1/8.

What is the probability of the spinner not landing on red?

(write the answer as a fraction in its lowest terms using the / sign e.g. 3/4) The probability of the spinner landing on green is 2/8 or 1/4.

What is the probability of the spinner not landing on green?

(write the answer as a fraction in its lowest terms using the / sign e.g. 3/4) The probability of picking a red card is 4/12.

What is the probability of not picking a red card?

(write the answer as a fraction in its lowest terms using the / sign e.g. 3/4) What is the probability of not picking a yellow card?

(write the answer as a fraction in its lowest terms using the / sign e.g. 3/4) What is the probability of not picking a blue card?

(write the answer as a fraction in its lowest terms using the / sign e.g. 3/4)

The probability that it will rain tomorrow is 5/7.

What is the probability that it will not rain?

(write the answer as a fraction in its lowest terms using the / sign e.g. 3/4)

The probability that it will rain tomorrow is 5/20.

What is the probability that it will not rain?

(write the answer as a fraction in its lowest terms using the / sign e.g. 3/4)

The probability that my train will be on time today is 7/16

What is the probability that it will not be on time?

(write the answer as a fraction in its lowest terms using the / sign e.g. 3/4)

The probability that my train will be on time today is 6/14

What is the probability that it will not be on time?

(write the answer as a fraction in its lowest terms using the / sign e.g. 3/4)

The probability that my lottery ticket will win the jackpot this week is 1/13983816.

What is the probability that it will not win the jackpot?

(write the answer as a fraction in its lowest terms using the / sign e.g. 3/4)

• Question 1 The probability of the spinner landing on red is 1/8.

What is the probability of the spinner not landing on red?

(write the answer as a fraction in its lowest terms using the / sign e.g. 3/4)

7/8
EDDIE SAYS
There are 7 outcomes that are not red out of 8 in total.
• Question 2 The probability of the spinner landing on green is 2/8 or 1/4.

What is the probability of the spinner not landing on green?

(write the answer as a fraction in its lowest terms using the / sign e.g. 3/4)

3/4
EDDIE SAYS
There are 6 outcomes that are not green out of 8 in total. Don't forget to cancel this down
• Question 3 The probability of picking a red card is 4/12.

What is the probability of not picking a red card?

(write the answer as a fraction in its lowest terms using the / sign e.g. 3/4)

2/3
EDDIE SAYS
There are 8 outcomes that are not red out of 12 in total. Don't forget to cancel this down
• Question 4 What is the probability of not picking a yellow card?

(write the answer as a fraction in its lowest terms using the / sign e.g. 3/4)

5/6
EDDIE SAYS
There are 10 outcomes that are not yellow out of 12 in total. Don't forget to cancel this down
• Question 5 What is the probability of not picking a blue card?

(write the answer as a fraction in its lowest terms using the / sign e.g. 3/4)

1/2
EDDIE SAYS
There are 6 outcomes that are not blue out of 12 in total. Don't forget to cancel this down
• Question 6

The probability that it will rain tomorrow is 5/7.

What is the probability that it will not rain?

(write the answer as a fraction in its lowest terms using the / sign e.g. 3/4)

2/7
EDDIE SAYS
These probabilities must add to 1 1 - (5/7)
• Question 7

The probability that it will rain tomorrow is 5/20.

What is the probability that it will not rain?

(write the answer as a fraction in its lowest terms using the / sign e.g. 3/4)

3/4
EDDIE SAYS
These probabilities must add to 1 1 - (5/20) Don't forget to cancel down
• Question 8

The probability that my train will be on time today is 7/16

What is the probability that it will not be on time?

(write the answer as a fraction in its lowest terms using the / sign e.g. 3/4)

9/16
EDDIE SAYS
These probabilities must add to 1 1 - (7/16)
• Question 9

The probability that my train will be on time today is 6/14

What is the probability that it will not be on time?

(write the answer as a fraction in its lowest terms using the / sign e.g. 3/4)

4/7
EDDIE SAYS
These probabilities must add to 1 1 - (6/14) Don't forget to cancel down
• Question 10

The probability that my lottery ticket will win the jackpot this week is 1/13983816.

What is the probability that it will not win the jackpot?

(write the answer as a fraction in its lowest terms using the / sign e.g. 3/4)

13983815/13983816
EDDIE SAYS
It is very likely that it will not win the jackpot! These probabilities must add to 1 1 - (1/13983816) Don't forget to cancel down
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