# Worksheet: Confidence Intervals for Population Means

In this worksheet, we will practice calculating 90%, 95%, and 99% confidence intervals for the population means.

Q1:

The weights of packets of chips are known to be distributed with a variance of 2.56 grams. A sample of 100 packs were tested and the mean weight was 24.1 grams.

Calculate a confidence interval for the population mean .

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• E

Q2:

A sample of the heights of people from a population resulted in a sample mean of meters. Given that the standard deviation, , is known, which of the following represents a confidence interval for the population mean?

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• B
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• E

Q3:

The number of hours students spend on homework each week is known to be distributed with a standard deviation of 3.21 hours. A sample of 50 students were asked how many hours they spend doing homework in a week and the results are given in the table.

 Hours Number of Students 3 4 5 6 7 8 9 10 11 4 5 8 10 4 7 9 2 1

Find the sample mean.

Calculate a confidence interval for the population mean.

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• B
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• E