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Research shows that many customers will only wait for up to four seconds for an e-commerce website to display images before giving up and moving to a different website. This customer behaviour costs businesses huge amounts of money each year.

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Research has found that the mean time for e-commerce websites to display images is 8.57 seconds with a standard deviation of 1.80 seconds. The display times for the websites are normally distributed.

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Give your answers to 4 decimal places.

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What is the probability that a website will take less than 4 seconds to display images? Give your answer to (4 decimal places).

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What is the probability that a website will take between 4 seconds and 7 seconds to display images? Give your answer to (4 decimal places).

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A display time of less than 4 seconds would be ideal. In a sample of 2000 websites, how many could be expected to load in less than 4 seconds?

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The CEO of a website design company believes that his company creates websites capable of displaying images faster than his competitor’s websites. He takes a sample of 30 websites designed by his company. The mean time for the sample (was 6.1 seconds with a sample standard deviation of 1.2 seconds.

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What is the 95% confidence interval for the true mean time for websites designed by this company to display images.

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