| Exam Board | OCR MEI |
|---|---|
| Module | S1 (Statistics 1) |
| Year | 2008 |
| Session | January |
| Marks | 8 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Independent Events |
| Type | Independent repeated trials |
| Difficulty | Moderate -0.8 This is a straightforward application of independent probability rules with clearly stated probabilities. Part (i) requires simple multiplication, part (ii) uses complement or addition rule, and part (iii) applies conditional probability formula. All are standard textbook exercises requiring only direct application of formulas with no problem-solving insight needed. |
| Spec | 2.03a Mutually exclusive and independent events2.03c Conditional probability: using diagrams/tables |
3 Steve is going on holiday. The probability that he is delayed on his outward flight is 0.3 . The probability that he is delayed on his return flight is 0.2 , independently of whether or not he is delayed on the outward flight.\\
(i) Find the probability that Steve is delayed on his outward flight but not on his return flight.\\
(ii) Find the probability that he is delayed on at least one of the two flights.\\
(iii) Given that he is delayed on at least one flight, find the probability that he is delayed on both flights.
\hfill \mbox{\textit{OCR MEI S1 2008 Q3 [8]}}