please help what i am i doing wrong

The International Baccalaureate (IB) program is an accelerated academic program offered at a growing number of high schools throughout the country. Students enrolled in this program are placed in accelerated r advanced courses and must take IB examinations in each of six subject areas at the end of grade 11 or grade 12. 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 a local high school, 15 grade 12 students attempted the IB mathematics exam, with these results. Exam Grade Number of Students UA W NH Calculate the mean x and standard deviation s for these scores. (Round your answers to two decimal places.) X = 4.33 S = 2.46 X