| Exam Board | WJEC |
|---|---|
| Module | Unit 4 (Unit 4) |
| Year | 2018 |
| Session | June |
| Marks | 7 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Probability Definitions |
| Type | Combined event algebra |
| Difficulty | Easy -1.2 This is a straightforward probability question testing basic set theory and conditional probability. Part (a) requires simple application of P(A∪B) = P(A) + P(B) - P(A∩B), part (b) is routine calculation of mutually exclusive events, and part (c) is a standard conditional probability formula P(B|A'). All techniques are direct recall with minimal problem-solving, making this easier than average. |
| Spec | 2.03a Mutually exclusive and independent events2.03d Calculate conditional probability: from first principles |
An architect bids for two construction projects. He estimates the probability of winning bid $A$ is $0 \cdot 6$, the probability of winning bid $B$ is $0 \cdot 5$ and the probability of winning both is $0 \cdot 2$.
\begin{enumerate}[label=(\alph*)]
\item Show that the probability that he does not win either bid is $0 \cdot 1$. [2]
\item Find the probability that he wins exactly one bid. [2]
\item Given that he does not win bid $A$, find the probability that he wins bid $B$. [3]
\end{enumerate}
\hfill \mbox{\textit{WJEC Unit 4 2018 Q1 [7]}}