| Exam Board | OCR MEI |
|---|---|
| Module | S1 (Statistics 1) |
| Year | 2008 |
| Session | January |
| Marks | 5 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Permutations & Arrangements |
| Type | Code/password formation |
| Difficulty | Easy -1.8 This is a straightforward application of basic counting principles requiring only simple multiplication. Part (i) uses 4×3×2=24 for arrangements without repetition, and part (ii) uses 4×4×4=64 with repetition allowed. These are textbook exercises with no problem-solving or conceptual challenge beyond direct recall of permutation formulas. |
| Spec | 5.01a Permutations and combinations: evaluate probabilities5.01b Selection/arrangement: probability problems |
2 Codes of three letters are made up using only the letters A, C, T, G. Find how many different codes are possible\\
(i) if all three letters used must be different,\\
(ii) if letters may be repeated.
\hfill \mbox{\textit{OCR MEI S1 2008 Q2 [5]}}