III.5. Grades in an economics course. If you choose four students at random from all those who have taken the course described in Exercise III.3, what is the probability that all the students chosen got a B or better? Simulate 10 repetitions of this random choosing and use your results to estimate the probability. (Your estimate from only 10 repetitions isn’t reliable, but if you can do 10, you could do 10,000.) (Hint: See page 447.)