CAIE A Level Mathematics 9709 · Probability

Probability: calculation question

2 marksFoundation

A bag contains 5 counters, 2 of which are red. One counter is taken at random. Find the probability that it is red.

(a)
Find the probability that the counter 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

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

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.