Discrete probability distributionsEdexcel A-Level Maths: Mind map

Exam questions on Discrete probability distributions

1. The discrete random variable $X$ has probability distribution $P(X=x)=kx$ for $x=1,2,3,4$, where $k$ is a constant.
   Two independent values of $X$ are observed. Find the probability that their sum is 3.2 marks
2. A fair eight-sided die has faces numbered 1 to 8. The random variable $X$ is the score when the die is rolled once.
   The die is rolled twice. Find the probability that the first score is greater than the second.2 marks
3. The discrete random variable $Y$ takes the values 0, 1, 2 and 3, with $P(Y=0)=0.15$, $P(Y=1)=a$, $P(Y=2)=2a$ and $P(Y=3)=a+0.05$.
   Find the value of $a$ and hence $P(Y\ge2)$.3 marks