The random variable X X\,X has the following probability distribution.
| xxx | 1 | 2 | 3 | 4 | 5 |
| P(X=x)P(X=x)P(X=x) | kkk | k2\displaystyle \frac{k}{2}2k | k3\displaystyle \frac{k}{3}3k | k4\displaystyle \frac{k}{4}4k | k5\displaystyle \frac{k}{5}5k |
where k k\,k is a constant.
Find the value of kkk.
The random variables X1 X_1\,X1 and X2 X_2\,X2 are independent and each have the same distribution as XXX. Find P(X1+X2=7)P(X_1 + X_2 = 7)P(X1+X2=7)
Practise Edexcel A Level Maths Statistical Distributions with exam-style questions for A Level Maths. 15 questions covering 6.1 Probability Distributions, 6.2 The Binomial Distribution, and 6.3 Cumulative Probabilities, matched to the Edexcel A Level Maths (9MA0) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.
