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4.6 Statistical hypothesis testing (A-level only)

4.6 Statistical hypothesis testing (A-level only)

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Question 47

A textile company produces spools of yarn. The length of yarn on each spool, Y Y\,Y m, is normally distributed with mean 150 m. Given that 25% of spools contain more than 154 m.

a.

Find the value of k k\,k such that P(k<Y<155)=0.60P(k < Y < 155) = 0.60P(k<Y<155)=0.60.

[4]
b.

The machinery is serviced so that the standard deviation of the length of yarn is now 5 m. Following the service, the supervisor believes that the mean length of yarn is less than 150 m. A random sample of 100 spools is checked and found to have a mean length of 149.2 m. Test the supervisor's belief at the 5% significance level. You should state your hypotheses clearly.

[5]
Markscheme

4.6 Statistical hypothesis testing (A-level only) Questions

  1. A Level
  2. /Maths
  3. /4.6 Statistical hypothesis testing (A-level only)

209 exam-style questions on CCEA A Level Maths 4.6 Statistical hypothesis testing (A-level only), covering 4.6.1 Statistical hypothesis testing (A-level only), 4.6.2 Statistical hypothesis testing (A-level only), 4.6.3 Statistical hypothesis testing (A-level only), 4.6.4 Statistical hypothesis testing (A-level only), and 4.6.5 Statistical hypothesis testing (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.

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