Question

A student is given data that follows a normal distribution. According to the data, the mean amount of time that students spent reading outside of school each month was 10 hours, and the standard deviation was 2 hours. Which percentage best represents the number of students that read between 8 and 12 hours outside of school in a month?

Answer 1

Convert to z-scores: z = (8−10)/2 = −1 and z = (12−10)/2 = 1.
About 68.27% of a normal distribution lies within ±1σ, so approximately 68% of students.