Higher June 2022 Paper 1 Q12

EdexcelHigherCurrent spec4 marksTree Diagrams

12 Rudolf goes to the gym.

The probability that he will use the treadmill is 0.8

When he uses the treadmill, the probability that he will use the cross trainer is 0.3
When he does not use the treadmill, the probability that he will use the cross trainer is 0.6

(a) Complete the probability tree diagram for this information. (2)

Probability tree diagram with blank branches: use treadmill or does not use treadmill, then use cross trainer or does not use cross trainer

(b) Work out the probability that Rudolf uses both the treadmill and the cross trainer. (2)

Mark scheme (a)

Scheme	Marks
0.8 and 0.2 0.3 and 0.7 0.6 and 0.4	B2
	(2)

Notes

B2: for all 3 correct pairs of probabilities on the correct branches
(B1 for 2 correct pairs of probabilities on the correct branches)
Allow equivalent fractions

Scheme	Marks
“0.8” × “0.3”	M1ft
0.24	A1ft
	(2)
	(4 marks)