Mathematics 9709 · AS & A Level · Sampling and estimation
Sampling and estimation — practice question
Human blood groups are described by two parts: the first part is A, B, AB or O, and the second part, the Rhesus part, is $+$ or $-$. In the UK, $35\%$ of the population are group A+, $8\%$ are B+, $3\%$ are AB+, $37\%$ are O+, $7\%$ are A$-$, $2\%$ are B$-$, $1\%$ are AB$-$ and $7\%$ are O$-$.
(i)[6]
A random sample of 9 people in the UK who are Rhesus $+$ is selected. Find the probability that fewer than 3 are group O$+$.
(ii)[5]
A random sample of 150 people in the UK is selected. Find the probability that more than 60 people are group A$+$.
Worked solution & mark scheme
This 11-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Hence $P(O\mid +)=\frac{0.37}{0.83}$” …