Andy has 4 red socks and 8 black socks in his drawer. He takes 2 socks at random from his drawer.
The random variable X is the number of red socks taken.
A fair die with faces numbered 1, 2, 2, 2, 3, 6 is thrown. The score, X, is found by squaring the number on the face the die shows and then subtracting 4.
A box contains 6 identical-sized discs, of which 4 are blue and 2 are red. Discs are taken at random from the box in turn and not replaced. Let X be the number of discs taken, up to and including the first blue one.
(i) Show that \(P(X = 3) = \frac{1}{15}\).
(ii) Draw up the probability distribution table for \(X\).
In a probability distribution the random variable \(X\) takes the value \(x\) with probability \(kx^2\), where \(k\) is a constant and \(x\) takes values \(-2, -1, 2, 4\) only.
Pack A consists of ten cards numbered 0, 0, 1, 1, 1, 1, 3, 3, 3, 3. Pack B consists of six cards numbered 0, 0, 2, 2, 2, 2. One card is chosen at random from each pack. The random variable X is defined as the sum of the two numbers on the cards.