c
Suppose that sixteen-ounce bags of chocolate chip cookies are produced with an actual mean weight of 16.1 ounces and a standard deviation of 0.1 ounce. The percentage of bags that will contain between 16.0 and 16.1 ounces is
a. 10
b. 16
c. 34
d. 68
e. non
e
Which statement is true for any density curve?
a. The bars must be of equal width.
b. It is symmetric.
c. It must either steadily rise or steadily fall, since it cannot do both.
d. One can use Table A (table of standard normal values) to find relative fre
c
Increasing the frequencies in the tails of a distribution will:
a. Not affect the standard deviation as long as the increases are balanced on each side of the mean
b. not affect the standard deviation
c. Increase the standard deviation
d. reduce the stand
a
Which of the following are true statements?
I. The area under a normal curve is always 1, regardless of the mean and standard deviation.
II. The mean is always equal to the median for any normal distribution.
III. The interquartile range for any normal cu
e
Pop1 and Pop2 are normal density curves with means and standard deviations mean1, st dev1, and mean2, st dev2, respectively. Suppose that mean1=mean2 and st dev1=2(st dev2). Consider these statements:
I. Pop1 has twice as many observations within one stan
b
A researcher wishes to calculate the average height of patients suffering from a particular disease. From patient record, the mean was computed as 156cm, and the standard deviation as 5cm. Further investigation reveals that the scale was misaligned, and t
c
A medical researcher collects health data on many women in each of several countries. One of the variables measure for each woman in the sudy is her weight in pounds. The following list gives the five-number summary for the weights of women in one of the
e
The mediam age of five people in a meeting is 30 years. One of the people, whose age is 50 years, leaves the room. THe mediam age of the remaining four people in the room is:
a. 40 years
b. 30 years
c. 25 year
d. less than 30 years
e. Cannot be determined
d
Earthquake intensities are measured using a device called a seismograph, which is designed to be most sensitive for earthquakes with intensities between 4.0 and 9.0 on the open-ended Richter scale. Measurements of nine earthquakes gave the following readi
d
The probability of any outcome of a random phenomenon is
a. the precise degree of randomness present in the phenomenon
b. any number as long as it is between 0 and 1
c. Either 0 or 1, depending on whether or not the phenomenon can actually occur or not
d.
a
A randomly elected student is asked to respond to yes, no, or maybe to the question, "Do you intend to vote in the next presidential election?" The sample space is {yes, no, maybe}. Which of the following represent a legitimate assignment of probabilities
c
If you choose a card at random from a well-shuffled deck of 52 cards, what is the probability that the card chosen is not a heart?
a. 0.25
b. 0.5
c. 0.75
d. 1
e. none of the above
b
You play tennis regularly with a friend, and from past experience, you believe that the outcome of each match is independent. For any given match you have a probability of .6 of winning. The probability that you win the next two matches is
a. 0.16
b. 0. 3
c
If P(A)=0.24 and P(B)=0.52 and A and B are independent, what is P(A or B)?
a. 0.1248
b. 0.28
c. 0.6352
d. 0.76
e. The answer cannot be determined from the information given.
When two events share no outcomes.
What is meant by disjoint (mutually exclusive) events?
When two events go along with each other to add up to 1.
Define complementary events
c
Suppose we fit the least squares regression line to a set of data. What do we call any individual points with unusually large values of the residuals?
a. response variables
b. the slope
c. outliers
d. correlations
e. none of the above
d
If removing an observation from a data set would have a marked change on the position of the LSRL fit to the data, what is the point called:
a. robust
b. a residual
c. a response
d. influential
e. none of the above
c
Which of the following statements are correct?
I. Two variables that are strongly associated will have a correlation near 1
II. Regression requires an explanatory-response relationship, while correlation does not.
III. Even though the correlation between
c
Recent data show that states that spend an above-average amount of money X per pupil in high school tend to have below-average mean Verbal SAT scores Y of all students taking the SAT in the state. In other words, there is a negative association between X
b
A researcher notices that in a sample of adults, those that take larger amount of vitamin C have fewer illnesses. However, those that take larger amounts of vitamin C also tend to exercise more. As explanations for having fewer illnesses, the variables "a
d
What do we call a sample that consists of the entire population?
a. stratum
b. a multistage sample
c. a mistake. A sample can never be the entire population
d. a census
e. none of the above
a
A member of Congress wants to know what his constituent think of proposed legislation on health insurance. His staff reports that 228 letters have been received on the subject, of which 193 oppose the legislation. What is the population in this situation?
c
Which of the following is a method for improving the accuracy of a sample?
a. Use no more than 3 or 4 words in any question
b. When possible, avoid the use of human interviewers, relying on computerized dialing instead
c. Use large sample sizes
d. Use sma
c
We say that the design of a study is biased if which of the following is true?
a. A racial or sexual preference
b. Random placebos have been used
c. certain outcomes are systematically favored.
d. The correlation is greater that 1 or less than -1
e. none
a
Control groups are used in experiments in order to...
a. control the effects of lurking variables such as the placebo
b. control the subjects of a study so as to insure all participate equally
c. guarantee that someone other than the investigators, who ha
No, a treatment is not imposed
Suppose the Richmond-Times dispatch asks a sample of 150 Richmonders their opinions on the quality of life in Richmond.
is this study an experiment? Why or why not?
d
In a statistics course, a linear regression equation was computed to predict the final exam score from the score on the first test. The equation was y=10+0.9x where y is the final exam score and x is the score on the first test. Carla scored 95 on the fir
b
In a statistics course, a linear regression equation was computed to predict the final exam score from the score on the first test. The equation was y=10+0.9x where y is the final exam score and x is the score on the first test. On the final exam Carla sc
b
All but one of the following statements contains a blinder. Which statement is correct?
a. The is a correlation of 0.54 between the position of a football player plays and his weight.
b. The correlation between planting rate and yield of corn was found to
no
In general, is correlation a resistant measure of association?
no, influential points effect it.
Is the least-squares regression line resistant? Why?
a
In a large population of college students, 20% of the students have experienced feelings of math anxiety. If you take a random sample of 10 students from this population, the probability that exactly 2 students have experienced math anxiety is
a. 0.3020
b
b
In a large population of college students, 20% of the students have experienced feelings of math anxiety. If you take a random sample of 10 students from this population, the standard deviation of of the number of students in the sample who have experienc
d
In a certain population, 40% of households have a total annual income of $70,000. A simple random sample of 4 of these households is selected. What is the probability that 2 or more of the households in the survey have an annual income of over $70,000?
a.
a
A factory makes silicon chips for use in computers. It is known that about 90% of the chips meet specifications. Every hour a sample of 18 chips is selected at random for testing. Assume a binomial distribution is valid. Suppose we collect a large number
c
Which of the following are true statements?
I. The expected value of a geometric random variable is determined by the formula p(1-p)^n-1
II. If X is a geometric random variable and the probability of success is .85, then the probability distribution of X
1. set n trials
2. success or failure (2 outcomes)
3. independent trials
4. p always stays the same
Describe the four conditions that describe a binomial setting.
c
Suppose X is a random variable with a mean. Suppose we observe X many times and keep track of the average of the observed values. The law of large numbers says that
a. The value of mean will get larger and larger as we observe X
b. As we observe X more an
c
In a population of students, the number of calculators owned is a random variable X with P(X=0)=0.2, P(X=1)=0.6, and P(X=2)=0.2. The mean of this probability distribution is
a. 0
b. 2
c. 1
d. 0.5
e. The answer cannot be computed from the imformation given
d
In a population of students, the number of calculators owned is a random variable X with P(X=0)=0.2, P(X=1)=0.6, and P(X=2)=0.2. The variance of this probability distribution is
a. 1
b. 0.63
c. 0.5
d. 0.4
e. the answer cannot be computed from the informat
c
The number of calories in a one0ounce serving of a certain breakfast cereal is a random variable with mean 110. The number of calories in a full cup of whole milk is a random variable with mean 140. for breakfast you eat one ounce of the cereal with 1/2 c
b
The weight of reports produced in a certain department has a normal distribution with mean 60g and standard deviation 12g. What is the probability that the next report will weight less than 45g?
a. 0.1042
b. 0.1056
c. 9,3944
d. 0.0418
e. The answer cannot