In this lesson, we will learn how to calculate 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 99% confidence interval for the population mean 𝜇.

Q2:

A sample of the heights of 𝑛 people from a population resulted in a sample mean of 𝑥 meters. Given that the standard deviation, 𝜎, is known, which of the following represents a 90% confidence interval for the population mean?

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.

Find the sample mean.

Calculate a 95% confidence interval for the population mean.

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