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Date November 2017 Marks available 2 Reference code 17N.2.AHL.TZ0.H_6
Level Additional Higher Level Paper Paper 2 Time zone Time zone 0
Command term Find Question number H_6 Adapted from N/A

Question

The number of bananas that Lucca eats during any particular day follows a Poisson distribution with mean 0.2.

Find the probability that Lucca eats at least one banana in a particular day.

[2]
a.

Find the expected number of weeks in the year in which Lucca eats no bananas.

[4]
b.

Markscheme

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

let X be the number of bananas eaten in one day

X Po ( 0.2 )

P ( X 1 ) = 1 P ( X = 0 )     (M1)

= 0.181   ( = 1 e 0.2 )     A1

[2 marks]

a.

EITHER

let Y be the number of bananas eaten in one week

Y Po ( 1.4 )     (A1)

P ( Y = 0 ) = 0.246596   ( = e 1.4 )     (A1)

OR

let Z be the number of days in one week at least one banana is eaten

Z B ( 7 ,   0.181 )     (A1)

P ( Z = 0 ) = 0.246596     (A1)

THEN

52 × 0.246596     (M1)

= 12.8   ( = 52 e 1.4 )     A1

[4 marks]

b.

Examiners report

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

Syllabus sections

Topic 4—Statistics and probability » SL 4.8—Binomial distribution
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Topic 4—Statistics and probability » AHL 4.17—Poisson distribution
Topic 4—Statistics and probability

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