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The Normal Distribution

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Question 11

The time taken for James to commute to work, in minutes, is normally distributed with a mean of 35 minutes and a standard deviation of 4 minutes. On a particular morning, James starts his commute.

a.

Find the probability that the commute takes longer than 32 minutes.

[1]
b.

James has already been commuting for 32 minutes. Find the probability that his commute lasts for another 8 minutes.

[4]
c.

James believes that the mean commute time is longer than 35 minutes. He records a random sample of 16 commutes and finds that their mean time is 36.8 minutes. Stating your hypotheses clearly and using a 5% level of significance, test James' belief.

[5]

The Normal Distribution Questions

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