Grade 12 · Statistics

Random variables

144 problems in this skill, each with a solver-verified answer key. Answers are checked the moment you submit — with a hint if you want one and a worked solution afterwards.

What the problems look like

A few statements from this skill. Answers, hints and worked solutions live in the practice session.

Warm-up
A random variable $X$ has mean $\mu_X = -8$ and standard deviation $\sigma_X = 4$ . Let $Y = 4X + 18$ . Find the mean $\mu_Y$ and the standard deviation $\sigma_Y$ of $Y$ .
Warm-up
A random variable $X$ has mean $\mu_X = 0$ and standard deviation $\sigma_X = 3$ . Let $Y = 6X - 20$ . Find the mean $\mu_Y$ and the standard deviation $\sigma_Y$ of $Y$ .
Warm-up
A random variable $X$ has mean $\mu_X = 14$ and standard deviation $\sigma_X = 9$ . Let $Y = 4X + 15$ . Find the mean $\mu_Y$ and the standard deviation $\sigma_Y$ of $Y$ .

Problems shown under their original terms: Generated (template, solver-computed).

Practice this free, right now

Unlimited math practice is on the free plan — no card, no trial clock.

Practice free Log in and practise this skill

See every Statistics skill for grade 12