Methods2025 Exam 1 · Q6Tech-free3 marks

Binomial variance and upper-tail probability

Consider the binomial random variable $X \sim \operatorname{Bi}\left(6, \frac{1}{4}\right)$ .

Find $\operatorname{var}(X)$ .

1 mark

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Determine $\Pr(X \geq 5)$ .

Give your answer in the form $\frac{a}{2^b}$ , where $a, b \in \Z$ .

2 marks

Hints, answer checking and worked solutions come with a Season Pass.