A-LevelMathematicsProbability and statistics9709/63 · Oct/Nov 2017 · Q46 Marks
A fair die with faces numbered 1, 2, 2, 2, 3, 6 is thrown. The score, X, is found by squaring the number on the face the die shows and then subtracting 4.
- (i)Draw up a table to show the probability distribution of X.[3]
- (ii)Find E(X) and Var(X).[3]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2017). The mark or mark type is shown in brackets.
- [B1] At least 3 different correct values of X (can be unsimplified)
- [B1] Four correct probabilities in a Probability Distribution table
- [B1] Correct probs with correct values of X
- [M1] Subst their attempts at scores in correct formula as long as 'probs' sum to 1
- [M1] Subst their attempts at scores in correct var formula
- [A1] Both answers correct
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