Question

# The American Film Institute discovered that the average American spent 78 hours viewing movies last year based on a study of 50 US people. This sample's standard deviation was nine hours. With the help of this,  develop a 95% confidence interval for the population mean number of hours spent watching movies last year.

Solution

Verified
$\overline{x}\pm t\cdot\dfrac{s}{\sqrt{n}},$
where $\overline{x}$ is the sample mean which is a point estimate of the population mean, the value of $t$ is found in the Student's $t$ Distribution table for the given confidence level and degrees of freedom, $s$ is the sample standard deviation, and $n$ is the number of observations in the sample.