User interface language: English | Español

Date None Specimen Marks available 3 Reference code SPNone.2.sl.TZ0.3
Level SL only Paper 2 Time zone TZ0
Command term Question number 3 Adapted from N/A

Question

A random variable X is distributed normally with mean 450. It is known that \({\rm{P}}(X > a) = 0.27\) .

Represent all this information on the following diagram.


[3]
a.

Given that the standard deviation is 20, find a . Give your answer correct to the nearest whole number.

[3]
b.

Markscheme


     A1A1A1     N3

Note: Award A1 for 450 , A1 for a to the right of the mean, A1 for area 0.27 .

[3 marks]

a.

valid approach     M1

e.g. \({\rm{P}}(X < a) = 1 - {\rm{P}}(X > a)\) , 0.73

\(a = 462.256 \ldots \)     A1

\(a = 462\)    A1     N3

[3 marks]

b.

Examiners report

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

Syllabus sections

Topic 5 - Statistics and probability » 5.9 » Normal distributions and curves.
Show 55 related questions

View options