Independence test with P(A∩B) = P(A)×P(B)

Questions that provide P(A), P(B), and P(A∩B) directly and ask to test independence using the product rule P(A∩B) = P(A)×P(B).

2 questions

Edexcel S1 2003 January Q2
2. A car dealer offers purchasers a three year warranty on a new car. He sells two models, the Zippy and the Nifty. For the first 50 cars sold of each model the number of claims under the warranty is shown in the table below.
ClaimNo claim
Zippy3515
Nifty4010
One of the purchasers is chosen at random. Let \(A\) be the event that no claim is made by the purchaser under the warranty and \(B\) the event that the car purchased is a Nifty.
  1. Find \(\mathrm { P } ( A \cap B )\).
  2. Find \(\mathrm { P } \left( A ^ { \prime } \right)\). Given that the purchaser chosen does not make a claim under the warranty,
  3. find the probability that the car purchased is a Zippy.
  4. Show that making a claim is not independent of the make of the car purchased. Comment on this result.
AQA Paper 3 2021 June Q14
14
  1. \(\quad\) Find \(\mathrm { P } ( A )\)
    14
  2. \(\quad\) Find \(\operatorname { P } ( B \mid A )\)
    14
  3. Determine if \(A\) and \(B\) are independent events.