The final score in a statistics course follows a normal distribution with mean 68

The final score in a statistics course follows a normal distribution with mean 68 and standard deviation 12.
(a)  What proportion of students in the course would pass if they need at least 50 to pass in the course?

(b) Suppose 5 students are randomly selected from those in the course. Then, what is the probability that exactly two of them will fail in the course if we apply the same standard as in (a).