CAIE A Level Mathematics 9709 · Probability

Probability: calculation question

2 marksFoundation

A bag contains 3 red marbles and 9 blue marbles. One marble is chosen at random. Find the probability that the marble is red.

(a)
Find the probability that the marble is red.
[2]

Work it out, then check it

Your working is checked step by step against the answer key, with method marks, units and carried-forward errors handled the way a mark scheme handles them.

Answer this and get it marked, free

Free account, no card. Three marked written answers a day on the free plan.

How this question is marked

2 marks. Method marks are awarded for correct working even if the final answer is wrong, and a later part can still score if it correctly uses an earlier wrong answer.

More Probability questions

3 marks · The probabilities of events A and B are given in the table below. Event Probability A frac35 B frac12 A ∩ B frac15 (i) Find P(A) × P(B) as…
3 marks · A survey of students recorded their gender and whether they passed a test. The results are shown in the table below. Passed Failed Total…
3 marks · The two-way table below shows the number of people who own a cat and who own a dog. Dog No dog Cat 3 4 No cat 2 1 One person is chosen at…
3 marks · A bag contains 4 red marbles and 2 blue marbles. Two marbles are drawn at random without replacement. Find the probability that both…
3 marks · A bag contains 4 red balls and 4 blue balls. A ball is drawn at random, its colour noted, and then replaced. A second ball is then drawn…
4 marks · In a school, the probability that a randomly selected student is in Year 10 is 0.25. If the student is in Year 10, the probability that…

All Probability questions

Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.