Statistics Paper 2 Statistical Inference 2020 Questions and Answers

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Centre Number Candidate Number
Pearson Edexcel
Level 3 GCE
Thursday 18 June 2020
Afternoon (Time: 2 hours) Paper Reference 9ST0/02

Statistics
Advanced
Paper 2: Statistical Inference

You must have: Total Marks
Statistical formulae and tables booklet
Calculator

Candidates may use any calculator permitted by Pearson regulations.
Calculators must not have retrievable mathematical formulae stored in them.
Instructions
•• Use black ink or ball-point pen.

• centre
If pencil is used for diagrams/sketches/graphs it must be dark (HB or B).
Fill in the boxes at the top of this page with your name,

• clearly labelled.
number and candidate number.
Answer all questions and ensure that your answers to parts of questions are

• Answer the questions in the spaces provided

• You
– there may be more space than you need.
should show sufficient working to make your methods clear.

• Unless
Answers without working may not gain full credit.
otherwise stated, inexact answers should be given to three

• Unless
significant figures.
otherwise stated, statistical tests should be carried out at the
5% significance level.
Information
•• AThere
booklet ‘Statistical formulae and tables’ is provided.

• – use this asfora guide
are 7 questions in this question paper. The total mark for this paper is 80.
The marks each question are shown in brackets
as to how much time to spend on each question.
Advice
•• Read each question carefully before you start to answer it.

•• Check
Try to answer every question.
your answers if you have time at the end.
If you change your mind about an answer, cross it out and put your new answer and
any working underneath.
Turn over



*P62710A0120*
P62710A
©2020 Pearson Education Ltd.

1/1/1/1/

, Answer ALL questions. Write your answers in the spaces provided.

1 The weights at 3 months of age, in kg, of baby girls born in the UK are modelled by the
normal distribution N(5.8, 0.742).
Rose has recently looked up the weights of a sample of 14 baby girls weighed at 3 months
of age in her clinic. The mean weight of the baby girls in her sample is 6.3 kg.
(a) Calculate a 95% confidence interval for the mean weight at 3 months of age of baby
girls in Rose’s clinic.
(3)
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, Question 1 continued
(b) Explain whether your answer to part (a) provides significant evidence that the mean
weight of baby girls at 3 months of age in Rose’s clinic is different from 5.8 kg.
(2)
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(c) State two assumptions needed for the confidence interval you calculated in part (a) to
be valid.
(2)
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(Total for Question 1 is 7 marks)




3
*P62710A0320* Turn over