4400 Higher June 2008 Paper 4 Q13
13 Each time Astrid takes a shot at goal, the probability that she will score is \(\dfrac{1}{3}\)
Astrid takes two shots.
(a) Complete the probability tree diagram.
(b) Calculate the probability that Astrid scores at least 1 goal. (3)
| Scheme | Marks |
|---|---|
| \(\frac{2}{3}\) correctly placed once | B1 |
| Correct structure | B1 |
| All correct | B1 |
| (3) |
Notes
B1: correct 4 new lines, ignore labels/probs
B1: including labels/probs
| Scheme | Marks |
|---|---|
| \(\frac{2}{3} \times \frac{2}{3}\) \(1 - \frac{2}{3} \times \frac{2}{3}\) or \(\frac{1}{3} + \frac{2}{3} \times \frac{1}{3}\) or \(\frac{1}{3} \times \frac{2}{3} + \frac{2}{3} \times \frac{1}{3} + \frac{1}{3} \times \frac{1}{3}\) | M1 M1 |
| \(\frac{5}{9}\) oe | A1 |
| (3) | |
| (6 marks) |
Notes
M1 M1: M1 for \(\frac{1}{3} \times \frac{2}{3}\) or \(\frac{2}{3} \times \frac{1}{3}\) or \(\frac{1}{3} \times \frac{1}{3}\)