| Exam Board | OCR |
|---|---|
| Module | Further Discrete (Further Discrete) |
| Year | 2018 |
| Session | September |
| Marks | 19 |
| Topic | Critical Path Analysis |
| Type | Explain dummy activities |
| Difficulty | Moderate -0.3 This is a comprehensive critical path analysis question covering standard techniques (dummy activities, early/late times, critical path, float calculations, cascade charts, resource allocation). While multi-part with 6 sections, each component is a routine application of well-defined algorithms taught in Decision Maths. The question requires careful bookwork rather than problem-solving insight, making it slightly easier than average for A-level. |
| Spec | 7.05a Critical path analysis: activity on arc networks7.05b Forward and backward pass: earliest/latest times, critical activities7.05c Total float: calculation and interpretation7.05d Latest start and earliest finish: independent and interfering float |
| Activity | A | B | C | D | E | F | G | H |
| Workers | 2 | 1 | 1 | 2 | 1 | 1 | 1 | 1 |
4 A project is represented by the activity network below. The times are in days.\\
\includegraphics[max width=\textwidth, alt={}, center]{22571082-016b-409b-bfeb-e7ebf48ccac7-4_384_935_1110_566}
\begin{enumerate}[label=(\roman*)]
\item Explain the reason for each dummy activity.
\item Calculate the early and late event times.
\item Identify the critical activities.
\item Calculate the independent float and interfering float on activity A .
\item (a) Draw a cascade chart to represent the project, using the grid in the Printed Answer Booklet.\\
(b) Describe the effect on
\begin{itemize}
\item the project completion
\item the critical activities\\
if the duration of activity D is increased by 5 days.
\end{itemize}
The number of workers needed for each activity is shown below.
\begin{center}
\begin{tabular}{ | l | c | c | c | c | c | c | c | c | }
\hline
Activity & A & B & C & D & E & F & G & H \\
\hline
Workers & 2 & 1 & 1 & 2 & 1 & 1 & 1 & 1 \\
\hline
\end{tabular}
\end{center}
The project needs to be completed in at most 3 weeks ( 21 days).\\
The duration of activity D is 9 days.
\item Find the minimum number of workers needed.
You should explain your reasoning carefully.
\end{enumerate}
\hfill \mbox{\textit{OCR Further Discrete 2018 Q4 [19]}}