PROBABILITYHigh school students in an International Baccalaureate (IB) program are placed in accelerated or advanced courses and must take IB examinations in each of six subject areas at the end of their junior or senior year. Students are scored on a scale of 1-7, with 1-2 being poor, 3 mediocre, 4 average, and 5-7 excellent. During its first year of operation at John W. North High School in Riverside, California, 17 juniors attempted the IB economics exam, with these results:
Exam grade, Number of students
7, 1
6, 4
5, 4
4, 4
3, 4
Calculate the mean and standard deviation for these scores.