A-LevelMathematicsProbability and statistics9709/63 · May/June 2023 · Q13 Marks
A random variable X has probability density function f, where f(x) = { (3/2)(1-x²) 0 ≤ x ≤ 1, 0 otherwise. } Find E(X).
- Find E(X).[3]
Mark scheme
Marking points from the official mark scheme (May/June 2023). The mark or mark type is shown in brackets.
- [1] Attempt to integrate xf(x) (i.e., ∫x(3/2)(1-x²)dx or equivalent); ignore limits.
- [1] Correct integration and limits: (3/2)[x²/2 - x⁴/4] from 0 to 1.
- [1] Final answer 3/8.
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