| Exam Board | AQA |
|---|---|
| Module | S1 (Statistics 1) |
| Year | 2008 |
| Session | June |
| Marks | 9 |
| Paper | Download PDF ↗ |
| Topic | Conditional Probability |
| Type | Basic two-way table probability |
| Difficulty | Easy -1.8 This is a straightforward two-way table probability question requiring only basic counting and division. All probabilities can be read directly from the table with minimal calculation. Part (d) and (e) involve conditional probability but use the simple definition P(A|B) = n(A∩B)/n(B), requiring no sophisticated reasoning—just identifying the correct cells and row/column totals. |
| Spec | 2.03a Mutually exclusive and independent events2.03b Probability diagrams: tree, Venn, sample space2.03c Conditional probability: using diagrams/tables2.03d Calculate conditional probability: from first principles |
| Colour | ||||
| Type | Black | Blue | Red | Green |
| Permanent marker | 44 | 66 | 32 | 18 |
| Non-permanent marker | 36 | 53 | 21 | 10 |
| Highlighter | 0 | 41 | 37 | 42 |
2 A basket in a stationery store contains a total of 400 marker and highlighter pens. Of the marker pens, some are permanent and the rest are non-permanent. The colours and types of pen are shown in the table.
\begin{center}
\begin{tabular}{|l|l|l|l|l|}
\hline
& \multicolumn{4}{|c|}{Colour} \\
\hline
Type & Black & Blue & Red & Green \\
\hline
Permanent marker & 44 & 66 & 32 & 18 \\
\hline
Non-permanent marker & 36 & 53 & 21 & 10 \\
\hline
Highlighter & 0 & 41 & 37 & 42 \\
\hline
\end{tabular}
\end{center}
A pen is selected at random from the basket. Calculate the probability that it is:
\begin{enumerate}[label=(\alph*)]
\item a blue pen;
\item a marker pen;
\item a blue pen or a marker pen;
\item a green pen, given that it is a highlighter pen;
\item a non-permanent marker pen, given that it is a red pen.
\end{enumerate}
\hfill \mbox{\textit{AQA S1 2008 Q2 [9]}}