Edexcel S1 2022 October — Question 3

Exam BoardEdexcel
ModuleS1 (Statistics 1)
Year2022
SessionOctober
TopicMeasures of Location and Spread
TypeCalculate variance/SD from coded sums

  1. Morgan is investigating the body length, \(b\) centimetres, of squirrels.
A random sample of 8 squirrels is taken and the data for each squirrel is coded using $$x = \frac { b - 21 } { 2 }$$ The results for the coded data are summarised below $$\sum x = - 1.2 \quad \sum x ^ { 2 } = 5.1$$
  1. Find the mean of \(b\)
  2. Find the standard deviation of \(b\) A 9th squirrel is added to the sample. Given that for all 9 squirrels \(\sum x = 0\)
  3. find
    1. the body length of the 9th squirrel,
    2. the standard deviation of \(x\) for all 9 squirrels.