| Date | May 2008 | Marks available | 4 | Reference code | 08M.1.sl.TZ2.14 |
| Level | SL only | Paper | 1 | Time zone | TZ2 |
| Command term | Find | Question number | 14 | Adapted from | N/A |
Question
When Andy plays tennis, \(65\% \) of his first serves go into the correct area of the court.
If the first serve goes into the correct area, his chance of winning the point is \(90\% \).
If his first serve does not go into the correct area, Andy is allowed a second serve and, of these, \(80\% \) go into the correct area.
If the second serve goes into the correct area, his chance of winning the point is \(60\% \).
If neither serve goes into the correct area, Andy loses the point.
Complete the tree diagram below.
Find the probability that Andy loses the point.
Markscheme
(A1)(A1) (C2)
[2 marks]
\(0.65 \times 0.1\) (\( = 0.065\)) (A1)
\(0.35 \times 0.8 \times 0.4\) (\( = 0.112\)) (A1)
\(0.35 \times 0.2 \times 1\) the 1 can be implied (\( = 0.07\)) (A1)(ft)
0.247 (A1)(ft) (C4)
Note: No (ft) for any probabilities greater than 1.
[4 marks]
Examiners report
This question proved to be the easiest question (along with question 1) with many candidates gaining full marks. The probability tree diagram was completed correctly and then most could go on to find the required probability. Very few added the probabilities instead of multiplying them.
This question proved to be the easiest question (along with question 1) with many candidates gaining full marks. The probability tree diagram was completed correctly and then most could go on to find the required probability. Very few added the probabilities instead of multiplying them.
