The speeds of vehicles traveling on a highway are normally distributed with a population standard deviation of 7 miles per hour and an unknown population mean. if a random sample of 20 vehicles is taken and results in a sample mean of 60 miles per hour, find a 98% confidence interval for the population mean.

Step-by-step explanation:

Given : The speeds of vehicles traveling on a highway are normally distributed .

Standard deviation:

Since , sample size : , which is small sample (n<30) so the test applied here is a t-test.

Degree of freedom=

Sample mean :

Level of significance :

Then , significance level :

Using t-distribution table , Critical value :

The confidence interval for population mean is given by :-

Hence, a 98% confidence interval for the population mean=

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step-by-step explanation:

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