How many different arrangements are there of the 11 letters in the word MISSISSIPPI?
- (i)How many different arrangements are there of the 11 letters in the word MISSISSIPPI?[2]
- (ii)Two letters are chosen at random from the 11 letters in the word MISSISSIPPI. Find the probability that these two letters are the same.[3]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2018). The mark or mark type is shown in brackets.
- [M1] 11! / (4!xk 2xk) k a positive integer
- [A1] Correct final answer
- [B1] One of P(SS), P(PP) or P(II) correct, allow unsimplified
- [M1] Sum of probabilities from 3 appropriate identifiable scenarios (either by labelling or of form (4a/11b * 2c/11b * 4a/11b) where a=4 or 3, b=11 or 10, c=2 or 1)
- [A1] Correct final answer
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