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Date November 2019 Marks available 3 Reference code 19N.1.AHL.TZ0.H_1
Level Additional Higher Level Paper Paper 1 (without calculator) Time zone Time zone 0
Command term Find Question number H_1 Adapted from N/A

Question

The probability distribution of a discrete random variable, X , is given by the following table, where N and p are constants.

Find the value of p .

[2]
a.

Given that E ( X ) = 10 , find the value of N .

[3]
b.

Markscheme

p = 1 1 2 1 5 1 5        (M1)

= 1 10        A1

[2 marks]

a.

attempt to find  E ( X )         (M1)

1 2 + 1 + 2 + N 10 = 10        A1

N = 65        A1

Note: Do not allow FT in part (b) if their p is outside the range 0 < p < 1 .

[3 marks]

b.

Examiners report

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

Syllabus sections

Topic 4—Statistics and probability » SL 4.7—Discrete random variables
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Topic 4—Statistics and probability » AHL 4.14—Properties of discrete and continuous random variables
Topic 4—Statistics and probability

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