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Date November 2016 Marks available 2 Reference code 16N.1.SL.TZ0.T_12
Level Standard Level Paper Paper 1 Time zone Time zone 0
Command term Complete Question number T_12 Adapted from N/A

Question

On a work day, the probability that Mr Van Winkel wakes up early is 45.

If he wakes up early, the probability that he is on time for work is p.

If he wakes up late, the probability that he is on time for work is 14.

The probability that Mr Van Winkel arrives on time for work is 35.

Complete the tree diagram below.

N16/5/MATSD/SP1/ENG/TZ0/12.a

[2]
a.

Find the value of p.

[4]
b.

Markscheme

* This question is from an exam for a previous syllabus, and may contain minor differences in marking or structure.

N16/5/MATSD/SP1/ENG/TZ0/12.a/M     (A1)(A1)     (C2)

 

Note:     Award (A1) for each correct pair of probabilities.

 

[2 marks]

a.

45p+15×14=35     (A1)(ft)(M1)(M1)

 

Note:     Award (A1)(ft) for two correct products from part (a), (M1) for adding their products, (M1) for equating the sum of any two probabilities to 35.

 

(p=) 1116 (0.688, 0.6875)    (A1)(ft)     (C4)

 

Note:     Award the final (A1)(ft) only if 0p1. Follow through from part (a).

 

[4 marks]

b.

Examiners report

[N/A]
a.
[N/A]
b.

Syllabus sections

Topic 4—Statistics and probability » SL 4.6—Combined, mutually exclusive, conditional, independence, prob diagrams
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Topic 4—Statistics and probability

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