GCSE · Basic probability
Probability of a single eventExam-style questions
Why a probability is a share of the whole — so it lives between 0 and 1, why P(A) = favourable ÷ total needs equally likely outcomes, and how the "it all adds to 1" rule drives complements, missing table entries and expected numbers.
13 questions · GCSE (Higher) level · mark scheme and worked solution on each · no sign-up to try
- 1Every ticket in a raffle is pink, yellow, blue or green.
One ticket is drawn at random to win the first prize.
Some of the probabilities are shown in the table.
The number of yellow tickets is times the number of green tickets.Colour of ticket pink yellow blue green Probability
(a) Work out the probability that the ticket drawn is green.
(3 marks)
of the tickets are blue.
(b) Work out how many tickets there are in the raffle.
(2 marks)Level 3 · 5 marksTry it - 2In one week, a factory made only red bicycles, black bicycles and silver bicycles.
For every red bicycles it made, the factory made black bicycles.
One of these bicycles is chosen at random for a safety check.
The probability that this bicycle is silver is
The factory made silver bicycles that week.
Work out how many black bicycles the factory made that week.
(4 marks)Level 3 · 4 marksTry it - 3A fair six-sided dice has faces numbered 1, 2, 3, 4, 5 and 6.
(a) Write down the probability that the dice lands on a number greater than 4.
The dice is rolled 180 times.
(b) Work out an estimate for the number of times the dice lands on a number greater than 4.Level 3 · 3 marksTry it - 4A bag contains only red beads, blue beads and green beads.
A bead is taken at random from the bag.
The probability that the bead is red is .
The probability that the bead is blue is .
The probability that the bead is green is .
(a) Work out the value of .
(b) Work out the probability that the bead is blue.Level 3 · 3 marksTry it