A-Level Maths Edexcel 9MA0

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#4 Use Normal distribution in hypothesis testing

For a random sample of size (n) taken from a random variable (X∼N(\mu, \sigma2)), the sample mean ((\bar{X})) is normally distributed with (\bar{X}∼N\bigg(\mu, \dfrac{\sigma^2}{n}\bigg)).

To perform the test:

  • Define the test statistic
  • Determine whether a one-tailed or two-tailed test is needed
  • Identify the null and alternate hypotheses accordingly
  • Calculate (P(\bar{X} < \bar{x})) and/or (P(\bar{X} > \bar{x}))
  • Compare with the significance level of the test (usually (5%)) and decide whether or not to reject the null hypothesis
  • Conclude with a statement in context of the question

[b]uSample mean of a Normally distributed random variable[/u]/b

(\bar{X}∼N\bigg(\mu, \dfrac{\sigma2}{n}\bigg))