CAIE A-Level Mathematics A2 5.4.3 Expectation and Variance Questions
Practise calculating and interpreting the expected value of a discrete random variable.
- Syllabus
- 2028–2030
- Course
- Mathematics 9709
- Level
- A2
Exam points
- calculate expected values from probability distributions
- use expected value to find unknown distribution parameters
- interpret the mean of a discrete random variable in context
CAIE A-Level Mathematics A2 5.4.3 Expectation and Variance Questions question 1
[Maximum number: 1]
Two fair coins are thrown at the same time repeatedly until a pair of heads is obtained. The number of throws taken is denoted by the random variable X.
State the value of E(X).
The probability of obtaining a pair of heads on one throw is 1/4. Therefore,
E(X)=1/41=4.
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