96 99 91 98 67 89 69 52 80 24 85 17 66 57

Above are the scores of a section of a course. For questions a-c, e-f, and i, suppose we know that scores are normally distributed.

1. Use the proper test to find if the average score is larger than 60.
2. Use the proper test to find if the Sd of scores is different compared to 25.
3. Use the proper test to find if a student who gets 80 in the course is "among the first one-third".
4. If we only know that the test scores are symmetrically distributed, use the proper test to find if the median is above 75.