Question 2: (10 marks) Circle the answer which is the closest to the correct answer.

1) Which of the following statements regarding the correlation is true.

A) The correlation is not sensitive to outliers.

B) 1 < r < 1.

C) If r is the correlation between X and Y , then r is the correlation between Y and X.

D) If r is the correlation between X and Y , then 2r is the correlation between 2X and Y .

E) None of the above.

2) A market research company wishes to find out which of two internet search engines the

population of students at a university prefers to use: Google or MSN Search. A random sample

of students is selected, and each one is asked to search for a certain subject using Google and

then MSN, or vice versa. The order of the two searches was determined at random. They then

indicate which internet search engine they prefer. What type of study is this?

A) An observational study. B) Completely randomized design.

C) A double-blind experiment. D) A matched-pairs experiment.

3) Suppose that A and B are two independent events with P(A) = 0.3 and P(B) = 0.3. Let

Bc be the complement of B. What is P(A and Bc

)?

A) 0.09 B) 0.21 C) 0.49 D) 0.60.

4) Which of the following is NOT an assumption of the Binomial distribution?

A) All trials must be independent.

B) Each trial must be classified as a success or a failure.

C) The number of successes in the trials is counted.

D) The probability of success is equal to .5 in all trials.

5) In hypothesis testing, the term "significant difference" refers to

A) the difference between the critical value and the test statistic.

B) the difference between the sample standard deviation and the population mean.

C) the difference between the sample mean and the hypothetical population mean that leads

to the rejection of the null hypothesis.

D) none of the above.

6) The AMS wants to survey students' opinions about the food services offered in the Student

Union Building. They take a simple random sample of 30 students from each faculty (Arts,

Science, Forestry, . . ., etc.). That is, they get 30 respondents from every faculty. What kind of

survey is this?

A) A probability sample. B) A stratified sample.

C) A simple random sample. D) None of the above.

7) Ignoring twins and other multiple births, assume babies born at a hospital are independent

events, with the probability that a baby is a boy and the probability that a baby is a girl both

equal to 0.5. Define the following events: event A = the next two babies are boys and event

B = the next two babies are girls. These two events are

A) disjoint. B) complements of each other. C) independent. D) both A) and B).

8) Suppose that a particular candidate for public office is in fact favored by p = 48% of all

registered voters. A polling organization is about to take a simple random sample of votes

and will use p, the sample proportion, to estimate p. How many votes need to be sampled to

guarantee that the standard deviation p is no more than 0.025?

A) 249 B) 399 C) 250 D) 400

9) In a hypothesis testing problem, the P-value tells us

A) if the null hypothesis is true.

B) if the alternative hypothesis is true.

C) the evidence against the null hypothesis.

D) the evidence against the alternative hypothesis.

10) The weight of a randomly selected book is a random variable with a mean of 1 kg and a

standard deviation of 0.5 kg. If we independently pick two books at random, the difference in

the weights of the two books is a random variable with a standard deviation (in kg) of

A) 0.00 B) 1.00 C) 1.41 D) 2.00 E) 0.707.