For a group of 10 men subjected to a stress situation, the mean number of heartbeats/min is 126 and the standard deviation was 4. Find the 95% confidence interval of the true mean?

1 Answer
AbhilashGM
Mar 12, 2018

The 95% confidence interval is 118 to 134.

Explanation:

The 95% confidence interval is plus/minus two standard deviations from the mean (1.96 to be exact, but 2 is a good approximate). Since the mean is 126, two standard deviations below the mean is 118 and two standard deviations above the mean is 134.

This means that in 95% of samples, the mean heartbeats/min will be in the range of 118 to 134.

Note, this assumes that the population is normally distributed.

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