Question

In a New York City high school, a survey revealed the mean amount of cola consumed each week was 12 bottles and the standard deviation was 2.8 bottles. Assuming the survey represents a normal distribution, how many bottles of cola per week will approximately 68.2% of the students drink?
1) 6.4 to 12
2) 6.4 to 17.6
3) 9.2 to 14.8
4) 12 to 20.4