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2.4 Statistical Distributions

2.4 Statistical Distributions

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Question 30

The lifetime of a certain type of battery is normally distributed with a mean of 48 hours and a standard deviation of 4.5 hours.

a.

Find the probability of a battery lasting longer than 55 hours.

[2]
b.

Write down a null and alternative hypothesis for a two-tailed test.

[1]
c.

A technician takes a sample of 20 batteries and finds a mean lifetime of 51 hours. Test at the 2% significance level whether there is evidence that the mean lifetime has changed.

[3]
Markscheme

2.4 Statistical Distributions Questions

  1. A Level
  2. /Maths
  3. /2.4 Statistical Distributions

390 exam-style questions on OCR A Level Maths 2.4 Statistical Distributions, covering 2.4.1 Discrete probability distributions, 2.4.2 Binomial distribution as a model, 2.4.3 Calculating binomial probabilities, 2.4.4 Mean and variance of the binomial (A-level only), 2.4.5 Normal distribution as a model (A-level only), 2.4.6 Probabilities using the normal distribution (A-level only), 2.4.7 Links to histograms, mean and standard deviation (A-level only), and 2.4.8 Selecting an appropriate distribution (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.

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