stats final practice: test 2

Below is a histogram of the number of 8-ounce glasses of water consumed by residents of a local nursing home during a typical day. (REFER TO TEST) 1.Approximately how many residents were included in this study? A) 8 B) 15 C) 44 D) 49 E) Not enough information 2.Approximately how many residents drank less than the recommended 8 glasses of water per day? 3. The overall shape of this distribution is A) roughly symmetric with no outliers. B) roughly symmetric with one outlier. C) clearly skewed left. D) clearly skewed right.

C) 44 38 B) roughly symmetric with one outlier

Below is a stemplot of the scores on a recent statistics test. (Key: 8|2 = 82%) 49 5 26 6 069 7 367788999 8 258 9 55 10 0 The overall shape of this distribution is A) clearly skewed to the right. B) clearly skewed to the left. C) roughly symmetric. D) without a clear shape.

C. roughly symmetrical

The 50th percentile of a distribution is A) the number with 50% of the data below it. B) the number with 50% of the data above it. C) the number with 50% of the data on either side of it. D) All of the above

D) All of the above

In all, 135 students took the statistics exam. The third quartile for all 135 scores is 69. About how many students had scores higher than 69? A)34 B)67 C)69 D)101

A) 34

A __________ tells us what values a variable takes and how often it takes those values. A) distribution B) quantity C) seasonal variation D) trend

A) distribution

Fifty percent of the observations will be between the A) first and third quartiles. B) mean plus or minus one standard deviation. C) mean plus or minus two standard deviations. D) mean plus or minus three standard deviations. E) mean and the standard deviation.

A) first and third quartiles.

For a distribution that is skewed to the right, usually the A) mean will be larger than the median. B) median will be larger than the mean. C) first quartile will be larger than the third quartile. D) standard deviation will be negative. E) minimum will be larger than the maximum.

A) mean will be larger than the median.

Suppose that the distribution of heart rates for medium-sized dogs is Normally distributed with mean 115 beats per minute and standard deviation 18 beats per minute. 1. Stacy takes her medium-sized dog, Scooter, to the veterinarian for a wellness check and learns that Scooter's heart rate is 126 beats per minute. What is the approximate standard score for Scooter's heart rate? A) -0.6 B) 0.6 C) 7 D) 11 E) 18 2. Approximately what percentage of medium-sized dogs have a heart rate that is lower than Scooter's? A) -60%. B) 27.42%. C) 60%. D) 72.58%. E) 99.4%. 3. Stacy learns from the veterinarian that dogs with heart rates in the upper 8% may be in danger of heart failure. For medium-sized dogs, a dangerous heart rate would be one above what value? A) 79 B) 189.8 C) 140.2 D) 151.2 E) 169 4. Approximately what percentage of medium-sized dogs have a heart rate below 115 beats per minute? A) 16% B) 34% C) 50% D) 68% E) 95%

B) 0.6 D) 72.58% C) 140.2 C) 50%

Scores of adults aged 60 to 64 on a common IQ test are approximately Normally distributed with mean 90 and standard deviation 15. 1. What range of IQ scores contains the central 95% of the population of adults aged 60 to 64? A) 75to105 B) 60to120 C) 30to150 D) 45to135 2. Suppose we call an IQ of 90 "normal" for adults aged 60 to 64. What percent of the population have "below normal" IQs? A) About 50% C) More than 50% B) Less than 50% D) Can't tell from the information given. 3. About what percent of the population of adults aged 60 to 64 have an IQ lower than 60? A) 90% B) 20% C) 16% D) 10% E) 2.5%

B) 60 A) About 50% E) 2.5%

The mean and the median of a distribution are measures of A) the number of observations. C) variability or spread. B) validity. D) center.

center

The weights of students in a large statistics class vary according to a Normal distribution with mean 145 pounds and standard deviation 18 pounds. 1. Approximately what range covers the middle 95% of the student weights? A) 136 to 154 pounds C) 109 to 181 pounds B) 127 to 163 pounds D) 91 to 199 pounds 2. Approximately what percent of the students weigh less than 145 pounds? A)16% B)34% C)50% D)84% E)95% 3. Approximately what percent of the students weigh more than 181 pounds? A)2.5% B)16% C)34% D)50% E)84% 4. The median weight of the students in this class is 5.A number with 60% of the data above it is A) the 60th percentile. C) always bigger than the mean. B) the 40th percentile. D) always smaller than the mean.

C) 109 to 181 pounds C) 50% A)2.5% 145 pounds B) the 40th percentile

Which of the following would indicate that a dataset is skewed to the right? A. The interquartile range is larger than the range. B. The range is larger than the interquartile range. C. The mean is much larger than the median. D. The mean is much smaller than the median.

C. The mean is much larger than the median.

A five-number summary for a data set is 35, 50, 60, 70, 90. About what percent of the observations are between 35 and 90? A. 25% B. 50% C. 95% D. 100%

D) 100%

The dean of admissions in a large university has determined that the scores of the freshman class in a mathematics test are normally distributed with a mean of 82 and a standard deviation of 8. Based on this information, what is the mean and standard deviation of the distribution of the sample mean if a sample of 64 students is selected at random from the entire freshman class? a. 64 and 10.25 b. 70 and 8.00 c. 80 and 2.50 d. 82 and 1.00 e. none of these

D) 82 and 1.00

The standard deviation is a measure of the A) center of a distribution. B) validity of a measurement. C) height of a histogram. D) spread or variability of a distribution. E) most common value in a set of data.

D) spread or variability of a distribution.

Ten members of a fraternity take a statistics course. Here are their scores on the first exam in the course: 61 74 47 60 62 63 65 79 55 85 To present the distribution of scores in a graph, you might choose a A) line graph. B) bar graph. C) pie chart. D) stemplot.

D) stemplot

Simpson's paradox occurs A) when association and causation are both present. B) when we analyze data using multiple regression. C) when the chi-square statistic's value is smaller than the P-value. D) when the nature of the observed relationship between two variables changes radically when we take into account other variables.

D) when the nature of the observed relationship between two variables changes radically when we take into account other variables.

By inspection, determine which of the following sets of numbers has the smallest standard deviation. A. 2,3,4,5 B. 4,4,4,5 C. 0,0,5,5 D. 5,5,5,5

D)5,5,5,5

An outlier is a data value that A. is larger than 1 million. B. equals the minimum value in a set of data. C. equals the maximum value in a set of data. D. is not consistent with the bulk of the data.

D. is not consistent with the bulk of the data

To display the percent of residents at least 65 years old in each of the 50 states in 2001, a good choice of a graph would be a A) box score. B) histogram. C) line graph. D) pie chart. E) bar graph.

E) bar graph.

One of the following 12 scores 8476 92 96 88 96 68 80 92 88 76 96 was omitted from the stemplot below: 6|8 7| 66 8| 0488 9 |2266 The missing score is

96

The following is a stemplot of 12 exam scores. (The stem is the tens place and the leaf is the ones place.): 6|8 7| 66 8 |0488 9| 22666 1. The median is 2. The mean is A) less than the median because the distribution is skewed left. B) greater than the median because the distribution is skewed left. C) less than the median because the distribution is skewed right. D) equal to the median. E) impossible to determine. 3. The first and third quartiles are, respectively, A) 76 and 92. B) 78 and 94. C) 94 and 78.

88 A) less than the median because the distribution is skewed left. B) 78 and 94.

Here is a set of data: 1300, 18, 25, 19, -7, 24. Which observation is the outlier?

1300

A student whose standardized score is 0.4 is at the 65.54th percentile. What percent of class scored higher than this student?

34.46%

Here are the number of hours that each of a group of students studied for an exam: 2 4 22 2 1 4 1 5 5 4 1. What is the median number of study hours? 2. What is the mean number of study hours? 3. What is the third quartile of the number of study hours? 4. The data contain one high outlier (22 hours). Which of your results for the previous four questions would change if this were five hours instead of 22 hours? (You do not need to calculate new values.) A) All four would change. B) The mean, the third quartile, and the standard deviation would change. C) The mean would change. D) Only the mean would change. E) None of the four would change.

4 5 5 D) only the mean would change

The following boxplot gives the distribution of the ratings of a new brand of peanut butter for 50 randomly selected consumers (100 points possible with higher points corresponding to a more favorable rating). refer to test Based on the box plot 1. The first quartile is: 2. The median is: 3. The third quartile is:

70 75 80

In order to be correct, a line graph of the number of suicides per year in the United States must have A) number of suicides on the horizontal scale. B) years on the horizontal scale. C) either suicides or years on the horizontal scale, as long as equal intervals are used. D) bars of equal width.

B) years on the horizontal scale.

You want to make a graph to display the distribution of the salaries of the 1700 professors at a large university. The best choice is a A) boxplot. D) pie chart. B) histogram. E) stemplot. C) line graph.

B) histogram

The possible values of the standard deviation s of a set of observations are A) s can be any number, positive, 0, or negative. B) s can be 0 or positive, but not negative. C) s can be positive, but not 0 or negative. D) s must be between -1 and 1. E) s must be between -1 and 1, but cannot be 0.

B) s can be 0 or positive, but not negative.

Your score on the statistics final exam is at the 70th percentile of the scores for the class. Your score lies A) below the first quartile. B) between the first quartile and the median. C) between the median and the third quartile. D) above the third quartile. E) Can't tell which quarter your score lies in.

C) between the median and the third quartile.