Grade point averages of students on a large campus follow a normal distribution with a mean of 2.6 and standard deviation of 0.5.

1. What is the minimum grade point average needed for a student's grade point average to be among the highest 10% on this campus?

2. A random sample of 400 students is chosen from this campus. What is the probability that at least 80 of these students have grade point averages higher than 3.0?

3. Two students are chosen at random from this campus. What is the probability that at least one of them has a grade point average higher than 3.0?