Probabilities that add to 1

The Maths Habit Handout to print

A bag holds 3 red and 9 green counters.
One is taken at random. Find P(red).
14
A fair spinner has 10 equal sections numbered 1 to 10. Find P(a multiple of 3).
310
A bag holds 2 pink, 5 white and 4 black beads. One is taken at random. Find P(not white).
611

In a class of 30, what is the chance
that two people share a birthday?

About 70%

Outcome: One possible result.

Outcome	Red	Blue	Green
Probability	0.5	0.3	0.2

Outcome	A	B	C	D
Probability	0.35	0.15	?	0.1

0.35A0.15BC0.1D

Outcome	Red	Blue	Green
Probability	0.2	0.45	?

Work out the probability of green. 0.35

0.2Red0.45Blue0.35Green

Outcome	A	B	C	D
Probability	0.3	0.12	?	0.4

Work out the probability of C. 0.18

Outcome	Red	Blue	Green
Probability	0.2	0.45	?

Work out the probability of green. 0.35

Outcome	Win	Draw	Lose
Probability	0.55	0.2	?

Work out the probability of lose. 0.25

Outcome	Red	Blue	Green
Probability	0.2	0.45	?

Work out the probability of green. 0.35

Outcome	Rain	No rain
Probability	?	0.64

Work out the probability of rain. 0.36

Outcome	Red	Blue	Green
Probability	0.2	0.45	?

Work out the probability of green. 0.35

Outcome	1	2	3	4
Probability	0.16	0.3	?	0.25

Work out the probability of 3. 0.29

Outcome	Red	Blue	Green
Probability	0.2	0.45	?

Work out the probability of green. 0.35

Outcome	Red	Yellow	Blue	Green	White
Probability	0.1	0.05	?	0.32	0.08

Work out the probability of blue. 0.45

Outcome	Win	Draw	Lose
Probability	12	13	?

12Win13DrawLose

Probabilities that add to 1 worksheet, page 1

Probabilities that add to 1 worksheet, page 2

Answer sheet

In a class of 30, the probability that nobody shares a birthday is 0.29. What is the probability that at least two people share a birthday?
0.71
A spinner lands on red, blue or green. Red and blue are equally likely. The probability of green is 0.4. What is the probability of red?
0.3

Outcome A B C D
Probability 0.25 0.4 ? 0.15
Find P(C).
0.2
Win, draw or lose. P(win) = 12, P(draw) = 15. Find P(lose).
310
Red, blue or green. Red and blue are equally likely. P(green) = 0.3. Find P(red).
0.35

Exit tickets to print