Date | November 2015 | Marks available | 2 | Reference code | 15N.2.hl.TZ0.1 |
Level | HL only | Paper | 2 | Time zone | TZ0 |
Command term | Find | Question number | 1 | Adapted from | N/A |
Question
The events A and B are such that P(A)=0.65, P(B)=0.48 and P(A∪B)=0.818.
Find P(A∩B).
[2]
a.
Hence show that the events A and B are independent.
[2]
b.
Markscheme
Note: In Section A, where appropriate, accept answers that correctly round to 2 sf except in Q2, Q5(a) (ii), Q5(b) and Q8(a).
0.818=0.65+0.48−P(A∩B) (M1)
P(A∩B)=0.312 A1
[2 marks]
a.
P(A)P(B)=0.312(=0.48×0.65) A1
since P(A)P(B)=P(A∩B) then A and B are independent R1
Note: Only award the R1 if numerical values are seen. Award A1R1 for a correct conditional probability approach.
[2 marks]
Total [4 marks]
b.
Examiners report
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a.
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b.