alleryA random variable X counts the number of heads in 3 tosses of a fair coin. The mean E(X) is
A1
B3
C2
D1.5
Answer & Solution
Correct answer: D. 1.5
1. X follows a Binomial distribution with n = 3, p = 1/2.
2. Mean of a Binomial random variable is E(X) = n × p.
3. So E(X) = 3 × 1/2 = 1.5.
4. Variance is n × p × q = 3 × 1/2 × 1/2 = 3/4.
_Source: syllabus Mathematics, Ch 13 "Probability", §13.6_
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