The discrete random variable X X\,X has the probability distribution given in the table below, where a a\,a is a constant.
| xxx | 0 | 1 | 2 | 3 |
|---|---|---|---|---|
| P(X=x)P(X = x)P(X=x) | 0.2 | 0.3 | 0.25 | aaa |
Find the value of aaa.
Find P(X>1.2)P(X > 1.2)P(X>1.2).
Find P(X≤x)P(X\le x)P(X≤x) for each of x=0,1,2,3x=0,1,2,3x=0,1,2,3.
390 exam-style questions on OCR A Level Maths 2.4 Statistical Distributions, covering 2.4.1 Discrete probability distributions, 2.4.2 Binomial distribution as a model, 2.4.3 Calculating binomial probabilities, 2.4.4 Mean and variance of the binomial (A-level only), 2.4.5 Normal distribution as a model (A-level only), 2.4.6 Probabilities using the normal distribution (A-level only), 2.4.7 Links to histograms, mean and standard deviation (A-level only), and 2.4.8 Selecting an appropriate distribution (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.