SAMPLING Distributions
Multiple Choice
Unit 6 Review
Older Chapters
Gimme Q's
100
A parameter is a number that describes a _______.
What is a population?
100
The student newspaper runs a weekly question that readers can answer online or by campus mail. One question was “Do you think the college is doing enough to provide student parking?” Of the 136 people who responded, 79% said “No”. The number 79% is a
(a) statistic (b) parameter (c) sample (d) population
What is A?
100
What is the Pythagorean Theorem of Statistics?
What is
sqrt(sigma^2+sigma^2
100
The shape of a distribution when the mean > median.
What is right skewed?
100
The pie chart above describes the distribution of favorite school subject for 300 high-school students. The number of students whose favorite subject is math is _____ .
What is 78?
200
The histograms below describe the values taken by three sample statistics in several hundred samples from the same population. The true value of the population parameter is marked on each histogram.
Which is preferred as an estimate of the parameter?
What is A?
(low bias AND low variability)
200
When a newspaper poll produces a statistic that is biased, it means that
(a) repeated polls would miss the truth about the population in the same direction.
(b) repeated polls would give results that are very different from each other.
(c) repeated polls give results that would not yield a normal distribution.
(d) repeated polls would give results that are very similar to each other.
What is A?
200
What is the difference between a discrete and a continuous random variable?
What is discrete has gaps and continuous has no gaps between the values?
200
Being unable to reach or contact members of the population leads to this type of bias.
What is undercoverage?
200
Which of the following are resistant to outliers?
(A) The mean and standard deviation.
(B) The median and standard deviation.
(C) The median and the IQR.
(D) The range and the IQR.
What is C?
300
The Gallup Poll has decided to increase the size of its random sample of voters from about 1500 people to about 4000 people right before an election. The poll is designed to estimate the proportion of voters who favor a new law banning smoking in public buildings. The effect of this increase is to
(a) reduce the bias of the estimate.
(b) increase the bias of the estimate.
(c) reduce the variability of the estimate.
(d) increase the variability of the estimate.
(e) reduce the bias and variability of the estimate.
What is C?
300
The central limit theorem can be used to determine the shape of a sampling distribution in which of the following scenarios?
(a) for a sample proportion when the population distribution is normal.
(b) for a sample mean when the population distribution is normal.
(c) for a sample proportion when the population distribution is not normal.
(d) for a sample mean when the population distribution is not normal.
What is D?
300
Patients receiving artificial knees often experience pain after surgery. The pain is measured on a subjective scale with possible values of 1 (low) to 5 (high). Let X be the pain score for a randomly selected patient. The following table gives part of the probability distribution for X.
Which probability is greater,
What is 
300
Name all the graphs that are used to represent one quantitative variable.
What are dotplot, stemplot, histogram, and boxplot?
300
Which of the distributions below has the larger standard deviation?
What is Distribution A?
400
About 10% of people in the United States do not wear a seat belt. Suppose we take a random sample of 180 U.S. residents, and let X = the number of people who do not wear their seat belt.
Calculate the probability that 26 or more individuals in the sample do not wear their seat belt. Assume all conditions are met.
What is about 0.0223?
400
A newspaper in a small town asks an SRS of 250 citizens, “Do you favor a law banning lawn mowing after 8 pm?” Suppose that 35% of all citizens favor the law. If we took a very large number of SRSs of size n = 250 from this population, the sampling distribution of the sample proportion pˆ would have which of the following characteristics?
(a) Mean 0.35, standard deviation 0.03, shape unknown.
(b) Mean 0.30, standard deviation 0.03, approximately normal.
(c) Mean 0.30, standard deviation 0.03, shape unknown.
(d) Mean 0.35, standard deviation 0.03, approximately normal.
What is D?
400
The weight of tomatoes chosen at random from a bin at the farmer’s market follows a Normal distribution with mean mu = 10 ounces and standard deviation sigma = 1 ounce. Suppose we pick four tomatoes at random from the bin and find their total weight T.
The random variable T is:
(a) Normal, with mean 10 ounces and standard deviation 1 ounce.
(b) Normal, with mean 40 ounces and standard deviation 2 ounces.
(c) Normal, with mean 40 ounces and standard deviation 4 ounces.
(d) binomial, with mean 40 ounces and standard deviation 2 ounces.
(e) binomial, with mean 40 ounces and standard deviation 4 ounces.
What is B?
400
Mrs. Garcia states the probability of a surprise quiz on any given day is 0.30. If quizzes are given independently of the day, what is the probability that there will be a surprise quiz on the next two consecutive days?
What is 0.09?
400
The five-number summary of the distribution of scores on the final exam in Psych 001 last semester was min=18 Q1= 39 Med = 62 Q3 = 76 Max = 100. A total of 416 students took the exam. About how many students had scores above 39?
What is 312 students?
500
A pediatrician has found that the heights of their patients follow a normal distribution with mean μ = 40 inches and standard deviation σ = 10.2 inches. Each day the doctor sees 15 patients, which can be considered a representative sample of the doctor’s patients. Each of their heights is recorded and the mean is calculated.
Find the probability that the mean height is greater than 52.2 inches. Assume all conditions are met.
What is about 0.0000018?
500
A psychologist studied the number of puzzles that subjects were able to solve in a five-minute period while listening to soothing music. Let X be the number of puzzles completed successfully by a randomly chosen subject. The psychologist found that X had the following probability distribution:
Let D be the difference in the number of puzzles solved by two randomly selected subjects in a five-minute period. What is the standard deviation of D?
(a) 0 (b) 0.81 (c) 0.9 (d) 1.27 (e) 1.8
What is D?
Use Pythagorean THM of Statistics!
500
According to Mars, Incorporated, 20% of its plain M&M’S candies are orange. Assume that the company’s claim is true. Suppose that you reach into a large bag of plain M&M’S (without looking) and pull out 8 candies. Let X = the number of orange candies you get.
Find the expected value and the standard deviation of X.
What is 1.6 and 1.13?
X is BINOMIAL!
500
It is known that 15% of the seniors in a large high school enter military service upon graduation. If a group of 20 seniors are randomly selected, what is the probability of observing 2 who will be entering the military?
What is 0.2293?
binompdf(trials=20,p=.15,x=2)
500
The most important advantage of experiments over observational studies is that
(A) experiments are usually easier to carry out.
(B) experiments can give better evidence of causation.
(C) confounding cannot happen in experiments.
(D) an observational study cannot have a response variable
What is B?