Mathematics 9709 · AS & A Level · Discrete random variables
Discrete random variables — practice question
In a particular country, the chance of getting more than $10\,\text{cm}$ of rain on any one day is $0.18$, independently of the weather on any other day.
(a)[3]
Determine the probability that, in any randomly selected $7$-day period, more than $2$ days have more than $10\,\text{cm}$ of rain.
(b)[3]
For $3$ randomly selected $7$-day periods, find the probability that exactly two of those periods have at least one day with more than $10\,\text{cm}$ of rain.
Worked solution & mark scheme
This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Apply the binomial probability expression for $P(X>2)=1-P(0,1,2)$” …