OCR MEI Further Statistics Minor 2021 November — Question 6

Exam BoardOCR MEI
ModuleFurther Statistics Minor (Further Statistics Minor)
Year2021
SessionNovember
TopicUniform Distribution
TypeCalculate basic probabilities

6 A lottery has tickets numbered 1 to \(n\) inclusive, where \(n\) is a positive integer. The random variable \(X\) denotes the number on a ticket drawn at random.
  1. Determine \(\mathrm { P } \left( \mathrm { X } \leqslant \frac { 1 } { 4 } \mathrm { n } \right)\) in each of the following cases.
    1. \(n\) is a multiple of 4 .
    2. \(n\) is of the form \(4 k + 1\), where \(k\) is a positive integer. Give your answer as a single fraction in terms of \(n\).
  2. Given that \(n = 101\), find the probability that \(X\) is within one standard deviation of the mean.