Dr. Clark claims to possess extrasensory perception (ESP). An experiment is conducted in which a person in one room picks one of the integers 1, 2, 3, 4, or 5 at random and concentrates on it for one minute. In another room, Dr. Clark identifies the number she believes was picked. The experiment is done with three trials. After the third trial, the random numbers are compared with Dr. Clarks predictions.

We can use binomial distributions to analyze the situation. We can compute the probability that the numbers would match by sheer random chance, without any extra help such as ESP.

Question #1: If a person merely guesses, what is the probability of a correct answer? (That is, what is the probability of a success?)

Response: the probability of a correct answer= p= 1/5 = 0.20

Question #2: Let X = number of correct guess in three trials. What is the sample space of X?

Response: Sample space ={0,1,2,3}

Question #3: Considering X has a binomial distribution, X ~ B(n, p). What are the values of n and p?

Response:n = 3 and p = 0.20

Question #4: What is the probability of each event in the sample space? Write your result in table form where you list the outcomes and the corresponding probabilities. Verify the probabilities sum to one.

Response:

x	P(X = x)
0	0.512
1	0.384
2	0.096
3	.008

You can also use the Binomial Distribution calculator on StatCrunch to verify these values. Go to Stat/Calculator/Binomial, enter the correct values for n and p, and choose a value for example Prob(X = 2).

Question #5: Interpret P(X=2) from the table above. What does this tell you about choosing numbers?

Response:

Question #6: Now lets return to Dr. Clark. She got the correct result twice. Does your work with the related binomial distribution support or refute her claim of ESP? Explain.

Response: