A math exam has 45 multiple choice questions, each with choices a to e. One student did not study and must guess on each question.

20.What is the mean of the normal distribution that approximates this binomial distribution?

a. 9b.36c. 90 d. 1e.0

21.What is the standard deviation of the normal distribution?

a.2.3b.3 c.2.6833d.4.125e.None of the above

22.Using normal approximation, estimate the probability that the student:

c) fails the exam i.e. gets 22 or fewer questions correct

a.0b..3212c..9999d..8673e..8297

23.gets five or more questions correct

a..65b..34c..09d..95e.None of the above

24.gets between 9 and 18 questions (both inclusively) correct

a..75b..57c..42d..53e.None of the above

25.Find the mean and standard deviation of the number of 4s obtained in 12 tosses of a fair die.

a)mean = 2,standard deviation = 1.29

b)mean = 3,standard deviation = 1.67

c) mean = 4,standard deviation = .67

d)mean = 0,standard deviation = 1

e)none of the above

26.Which of the following is false, think about the continuity correction:

a)P(at least 5 successes) = P(r 5) = P(X 4.5)

b)P(more than 5 successes) = P(r 6) = P(X>5.5)

c)P(less than 5 successes) = P(r 4) = P(X< 4.5)

d)P(at most 5 successes) = P(r 5) = P(X 4.5)

e)None of the above

27.The life of a vacuum cleaner is normally distributed with mean 2.0 years and std dev. 1.0year.

Find the probability that it lasts less than 3.6 years. (4 decimal places)

a).0312b).8762c).0548d).9452e)None of the above

28.Approximate the value of z alpha where alpha = .20

a)2.576b).842c)1.645d)1

e)None of the above