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?