On any day in January, the probability the temperature at a weather station is above 14°C is 0.35 . There are 31 days in January. Find the number of days in January when you would expect the temperature to be above 14°C.
- (a)(i)On any day in January, the probability the temperature at a weather station is above 14°C is 0.35 . There are 31 days in January. Find the number of days in January when you would expect the temperature to be above 14°C.[1]
- (a)(ii)(a)The temperature on two consecutive days in January is recorded. Complete the tree diagram.[2]
- (a)(ii)(b)Find the probability that the temperature is above 14°C on both days.[1]
- (a)(ii)(c)Find the probability that the temperature is above 14°C on only one of the two days.[2]
- (b)In a group of 14 children: • 8 wear red T-shirts • 1 wears a green T-shirt • 5 wear blue T-shirts. Two children are chosen from the group at random. Find the probability that they wear different coloured T-shirts.[3]
This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.
Mark scheme
Marking points from the official mark scheme (May/June 2024). The mark or mark type is shown in brackets.
- [1] 10 or 11
- [2] Correct tree diagram
- [2] M1 for 2 or 3 probabilities completed correctly
- [2] 0.65, 0.65, 0.35, 0.65 oe
- [1] 0.1225 oe e.g. 49/400
- [2] 0.455 oe e.g. 91/200
- [2] M1 for [2x]0.35×0.65
- [3] 106/182 oe e.g. 53/91
- [3] M2 for 1 - ( (8/14)*(7/13) + (1/14)*(0/13) + (5/14)*(4/13) ) oe
- [3] or (8/14)*(6/13) + (1/14)*(13/13) + (5/14)*(9/13) oe
- [3] or M1 for (8/14)*(7/13) + (1/14)*(0/13) + (5/14)*(4/13) oe or 3 correct products
- [3] After 0 scored, SC1 for 106/196 e.g. 53/98 oe
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