Marcelina has over
songs on her mobile phone, and she wants to estimate the average length of the songs (in minutes). She takes an of
songs on her phone and calculates a sample mean of
minutes and a standard deviation of
minutes. The song lengths in the sample were roughly symmetric with no clear outliers.
Based on this sample, which of the following is a
confidence interval for the mean length (in minutes) of the songs on her phone?