Intermediate June 2017 Unit 1 Q6
6. David, Jane and Mary are beach inspectors.
Three beaches, Harlech, Rhyl and Porthcawl, are all to be inspected on a certain day.
It is decided to share the work so that the inspectors will visit one beach each, chosen at random.
(a) List all the possible different ways they could share the work.
One has been done for you. [2]
One has been done for you. [2]
David ⟶ Harlech, Jane ⟶ Rhyl and Mary ⟶ Porthcawl
(b) What is the probability that one of the female inspectors will visit Rhyl? [2]
| Scheme | Marks | Comments |
|---|---|---|
| ( David – Hr Jane – Rh Mary – P ) David – Hr Jane – P Mary – Rh David – Rh Jane – Hr Mary – P David – Rh Jane – P Mary – Hr David – P Jane – Hr Mary – Rh David – P Jane – Rh Mary – Hr | B2 | Allow any unambiguous notation e.g. ‘DH’. For all other 5 different combinations. Do not penalise repeats. B1 for 3 or 4 other different combinations. B0 otherwise. |
| Scheme | Marks | Comments |
|---|---|---|
| \(\dfrac{4}{6}\) or equivalent. ISW | B2 | 2/3 or 4/6 gains B2 regardless of their list. B1 for x/6 (x<6) OR 4/y (y>4) F.T. ‘their list’ (using different combinations) if at least 4 to choose from for B2 or B1 as appropriate. |