A-LevelMathematicsProbability and statistics9709/52 · Feb/Mar 2023 · Q53 Marks
Marco has four boxes labelled K, L, M and N. He places them in a straight line in the order K, L, M, N with K on the left. Marco also has four coloured marbles: one is red, one is green, one is white and one is yellow. He places a single marble in each box, at random. Events A and B are defined as follows. A: The white marble is in either box L or box M. B: The red marble is to the left of both the green marble and the yellow marble. Determine whether or not events A and B are independent.
Mark scheme
Marking points from the official mark scheme (Feb/Mar 2023). The mark or mark type is shown in brackets.
- [B1] P(A) = 1/2. P(B) = 8/24 = 1/3. Both stated, accept unsimplified.
- [M1] Evidence that independence properties not used.
- [A1] Evaluated and conclusion stated. P(A) × P(B) and P(A∩B) seen.
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