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2.4.2 The Normal distribution (A-level only)

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Question 48

The mass of a high-precision turbine blade, in grams, is modelled by a Normal distribution with mean 450.0 g and standard deviation 12.4 g.

After a change to the manufacturing process, a quality control engineer suspects that the mean mass of the blades has decreased. A random sample of 50 blades is measured and the sample mean mass is found to be 446.2 g.

a.

Stating your hypotheses clearly, carry out a test at the 2% significance level to investigate the engineer's suspicion. You may assume that the standard deviation is still 12.4 g.

[5]
b.

State one assumption, other than the value of the standard deviation, that the engineer has made in carrying out this test.

[1]
Markscheme

2.4.2 The Normal distribution (A-level only) Questions

  1. A Level
  2. /Maths
  3. /2.4.2 The Normal distribution (A-level only)

351 exam-style questions on AQA A Level Maths 2.4.2 The Normal distribution (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.

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