Higher June 2018 Paper 3 Q4
4 When a biased 6-sided dice is thrown once, the probability that it will land on 4 is 0.65
The biased dice is thrown twice.
Amir draws this probability tree diagram.
The diagram is not correct.
Write down two things that are wrong with the probability tree diagram. (2)
| Answer | Mark | Mark scheme |
|---|---|---|
| Probabilities should sum to 1 | C1 | for stating that the probabilities should total 1 eg 0.25 should be 0.35 |
| 0.35 and 0.65 reversed | C1 | for recognising that the 0.35 and 0.65 in the first branches for the 2nd throw should be reversed eg, “for the second throw, the probability it lands on 4 should be 0.65” |
Additional guidance
Can be shown on the diagram