Assuming that the scores (%) for your midterm exam follow a normal model N(77,12) and there are 46 students who took the midterm:

1. How many students do you expect to have a grade higher than 85%? (2 marks)

2. What is the probability of a student obtaining a score lower than 50%?

3. What is the probability of a student obtaining a score higher than 90%?

4. What is the probability of a student obtaining a score between 60% and 80%