| Exam Board | Edexcel |
|---|---|
| Module | S2 (Statistics 2) |
| Year | 2004 |
| Session | January |
| Marks | 7 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Discrete Probability Distributions |
| Type | Direct probability from given distribution |
| Difficulty | Easy -1.3 This is a straightforward S2 question testing basic probability calculations for three standard distributions (binomial, Poisson, normal). Each part requires only direct application of formulas or tables with no problem-solving, conceptual insight, or multi-step reasoning—purely routine computational exercises that are easier than typical A-level questions. |
| Spec | 2.04c Calculate binomial probabilities2.04f Find normal probabilities: Z transformation5.02k Calculate Poisson probabilities |
The random variable $R$ has the binomial distribution B(12, 0.35).
\begin{enumerate}[label=(\alph*)]
\item Find P($R \geq 4$). [2]
\end{enumerate}
The random variable $S$ has the Poisson distribution with mean 2.71.
\begin{enumerate}[label=(\alph*)]
\setcounter{enumi}{1}
\item Find P($S \leq 1$). [3]
\end{enumerate}
The random variable $T$ has the normal distribution N(25, $5^2$).
\begin{enumerate}[label=(\alph*)]
\setcounter{enumi}{2}
\item Find P($T \leq 18$). [2]
\end{enumerate}
\hfill \mbox{\textit{Edexcel S2 2004 Q2 [7]}}