Economics 310 Menzie D. Chinn
Fall 2003 Social Sciences 7418
University of Wisconsin-Madison
Practice Midterm Exam 1
Answer all questions in your bluebook. Make certain you write your name, your student
ID number, and your TA’s name on your bluebook.
Point allocations are proportional to time allocations.
1. (10 minutes) Many firms use on-the-job training to teach their employees
computer programming. Suppose you work in the personnel department of a firm
that just finished training a group of its employees to program, and you have been
requested to review the performance of one of the trainees on the final test that
was given to all trainees. The mean and standard deviation of the test scores are
80 and 5, respectively, and the distribution of scores is mound-shaped. If a firm
wanted to give the best 2.5% of the trainees a big promotion, what test score
would be used to identify the trainees in question?
2. (10 minutes) The Tampa fire department reviewed all telephone calls of
emergency made over the past 15 years and have claimed that the chance that any
given call is a false alarm is only 10%. Suppose that three calls from that time
period are randomly selected. Find the probability that exactly two of the three
calls selected turned out to be false alarms.
3. (10 minutes) An experiment is to be conducted to determine whether an
acclaimed stock market analyst has extrasensory perception (ESP). Five different
cards are shuffled and one is chosen at random. The analyst will try to identify
which card was drawn without seeing it. The experiment is repeated 10 times and
x, the number of correct decisions, is recorded. If the analyst is guessing (and
does not possess ESP), what is the probability that the analyst gets exactly four of
the 10 trials correct?
4. (20 minutes total) In a certain city, 10 percent of the people are fascists, 70% are
socialists and 20% are communists. Records indicate that in the last election, 65%
of the fascists voted, 82% of the socialists and 50% of the communists. If a person
in the city is selected at random and
(a) (5 minutes) it is learned that she voted in the last election, what is the
probability that she is a socialist?
(b) (15 minutes) it is learned that she did not vote in the last election, what is the
probability that she is either a fascist or communist?
