O-LevelMathematicsProbability4024/12 · Oct/Nov 2020 · Q154 Marks
Two bags contain beads. The first bag contains 7 beads, of which 3 are red and 4 are white. The second bag contains 5 beads, of which 2 are red and 3 are blue. One bead is taken, at random, from each bag. The tree diagram is shown below.
- (a)Find the probability that both beads are red,[1]
- (b)both beads are white,[1]
- (c)exactly one bead is red.[2]
This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2020). The mark or mark type is shown in brackets.
- [1] 15(a) 6/35 oe
- [1] 15(b) 0 oe
- [2] 15(c) 17/35 oe
- M1 for 3/7 x 3/5 oe or 4/7 x 2/5 oe
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