2. A newly hired telemarketer is told he will probably make a sale on about 12% of his phone calls. The first week he called 200 people, but only made 10 sales. Should he suspect he was misled about the true success rate?

3. Scientists wish to test the mind-reading ability of a person who claims to “have ESP.” They use five cards with different and distinctive symbols (square, circle, triangle, line, squiggle). Someone picks a card at random and thinks about the symbol. The “mind reader” must correctly identify which symbol was on the card. If the test consists of 100 trials, how many would this person need to get right in order to convince you that ESP may actually exist? Explain.

4. A lecture hall has 200 seats with folding arm tablets, 30 of which are designed for left-handers. The average size of classes that meet there is 188, and we can assume that about 13% of students are left-handed. What’s the probability that a right-handed student in one of these classes is forced to use a lefty arm tablet?

5. A grocery supplier believes that in a dozen eggs, the mean number of broken ones is 0.6 with a standard deviation of 0.5 eggs. You buy 3 dozen eggs without checking them.
How many broken eggs do you expect to get?
What’s the standard deviation?

6. TEST TOPICS What is probability?
Law of Large Numbers – In the long run . . .
Independent Events (Multiplication Rule)
Complement Rule
Disjoint Events (mutually exclusive)

7. General Addition Rule P(A U B) = P(A) + P (B) – P(A ∩ B)
General Multiplication Rule
Tree Diagrams
Drawing With/Without Replacement
Expected Value Problem
Bernoulli Trials
Binom (n,p) Link to the Normal Model
n = number of trials Mean/Standard Deviation
p = probability of success
X = number of successes in n trials
Permutations/Combinations

8. Dishwashers
Dan’s Diner employs three dishwashers, Al washes 40% of the dishes and breaks only 1% of those he handles. Betty and Chuck each wash 30% of the dishes, and Betty breaks only 1% of hers, but Chuck breaks 3% of the dishes he washes. You go to Dan’s for supper one night and hear a dish break at the sink. What’s the probability that Chuck is on the job?