Question

Suppose the distribution of Y = the amount of time it takes for a randomly selected student to complete a particular exam is normal with mean 43.7 minutes and standard deviation 4.6 minutes. Suppose those students who go past a 50 minute time limit are tortured by Dr. Robinson’s singing until they complete the exam.

a. Show that the probability of a randomly selected student avoiding any torture is .91459. (6 decimals)

b. If 10 students take the exam, what is the probability that at least one of them is tortured for some period of time? (5 decimals)

c. If a randomly selected student is in fact tortured, what is the probability that he/she is tortured for less than 3 minutes? (5 decimals) (Extra Credit)

Suppose Dr. Johnson is really mean, and without warning requires the students to hand in their exams at the end of the 50 minute period.

a.The median amount of time spent by students taking the exam would be:

      A. unchanged B. decreased C. decreased

b.The mean amount of time spent by students taking the exam would be:

      A. unchanged B. decreased C. increased

c.The distribution of the amount of time spent by students taking the exam would be:

      A. skewed negatively B. skewed positively C. symmetric

Answer 1