Sum and product lawsEdexcel International A Level Maths: Flashcards

What these 13 flashcards ask

State the sum law for two events.
What does A\cup B mean?
What does A\cap B mean?
Probability of the complement A'?
When are two events mutually exclusive?
State the product law.
Condition for independent events?
How do you test whether A and B are independent?
Rule for multiplying and adding on a tree diagram?
What must the probabilities leaving one point of a tree diagram add to?
How does sampling without replacement change the probabilities?
Quickest way to find 'at least one'?
Where do you start filling in a Venn diagram?

Exam questions on Sum and product laws

Events $A$ and $B$ are such that $P(A)=0.4$ , $P(B)=0.5$ and $P(A\cap B)=0.15$ .
Find the probability that neither $A$ nor $B$ occurs.2 marks
A bag contains 5 red discs and 3 blue discs. Two discs are taken from the bag at random, one after the other, without replacement.
Find the probability that at least one of the two discs is red.2 marks
A factory has two machines. Machine $X$ makes 60% of the components and machine $Y$ makes the other 40%. Each component from $X$ is defective with probability 0.05, and each component from $Y$ is defective with probability 0.02, independently of all others.
Find the probability that a component chosen at random from the factory's output is defective.3 marks

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).