AP Statistic Final Exam
There are 2 questions in a study The probability that Q1 was right and Q2 was wrongwas .08 // The probability that Q2 was right and Q1 was wrong is .2 // The prob that both are right is .25 // The prob that both are wrong is .47 What must be true if A= Question 1 is correct B= Question 2 is correct ) A and B are independent because each question is correct with probability .5 and the probability that both questions are answered correctly is (.5)(.5)=.25 ) A and B are not independent because the probability in each cell is not .25 ) A and B are not independent because (.33)(.45)=/ .25 ) A and B are independent because one person's answers do not affect anothers )Not enough infomation
) A and B are not independent because (.33)(.45)=/ .25
Population H is a group of women with normally distributed heights. Population H has a population mean of 66 inches with a standard dev of 2.5 inches. Z-score associated with the height 65 inches? ) z= -1 ) z= -.5 ) z= -.4 ) z= .4 ) z= 1.4
-0.4
Probability accounted for .1 6C What does C equal ) .1 ) .15 ) .2 ) .25 ) .75
.15
P(X) =.25 and P(Y)= .4 If P(X|Y) = .2, what is P(Y|X)? ) .1 ) .125 ) .32 ) .45 ) .5
.32
What is the probability of a randomly drawn marble being yellow, given that it is small ) .39 ) .64 ) .14 ) .37 ) .23
.39
Tropical Storm Question ) .045 ) .125 ) .17 ) .4 ) .96
.4
What is the probability that a randomly selected marble will be blue or white ).34 ).16 ).5 ).18 ) None of the above
.5
If P(A) =.25 and P(B)= .34 what is P(A union B) if A and B are independent? ) .085 ) .505 ) .590 ) .675 )Insufficient info
.505
Only 7.2% of the American population has -O blood. If ten people appear at random to give blood, what is the probability that at lease 1 is a universal donor? ) 0 ) .28 ) .526 ) .72 ) 1
.526
y= 2.4 - 0.2x // Calculate the residual for a block with 10 streetlights and 1 crime a month ) -.6 ) .6 )-.4 ) .4 ) -1.2
.6
Fin the probability of a marble being large and black ) .35 ) .65 ) .22 ) .2 ) .8
.65
Number of adults 1, 2, 3, 4 Probability .25, .5, .15, .1 What is the standard deviation of the probability distribution ) 2.1 ) 0.89 ) 0.79 ) 0.62 ) 0.5
.89
Molly earned a score of 940 on a test. The mean was 850 with a standard dev of 100. What proportion of students had a higher score than molly? ) 0.90 ) 0.82 ) 0.40 ) 0.18 ) 0.10
0.18
Let the random variable X represent the profit made on a randomly selected day by a certain store. Assume that Z is Normal with mean of 360 and standard deviation of 50. What is P(X>400) ) 0.2119 ) 0.2811 ) 0.5319 ) 0.7881 ) 0.8450
0.2119
(0,.24) , (1,.37), (2, .20) , (3, .11), (4, .05), (5, .03) What is the probability that a randomly chosen household has at least 2 cars ) .19 ) .2 ) .29 ) .39 ) .61
0.39
The probability a child will have alcohol problems is .75% if at least 1 parent is an alcoholic and .05 if neither parent is an alcoholic. In a study 5% of the children had at least one alcoholic parent. If a child in this study has a alcohol problem, what is the probability that one of the parents is an alcoholic ) 0.0375 ) 0.0475 ) 0.4412 ) 0.7895 ) 0.8
0.4412
The avg. noise level in a bar is 36 decibels with a standard deviation of 5 decibels. Assuming a normal distribution, what is the probability the noise level is between 30 and 40 decibels ) 0.327 ) 0.337 ) 0.381 ) 0.673 ) 0.683
0.673
y= 2.4 - 0.2x // How many crimes a month are predicted when there are 7 streetlights on a block? ) 3.8 ) 1.7 ) 16.6 ) -11.6 ) 1
1
It is estimated that 20% of all drivers do not signal when not changing lanes. In a random sample of 4 drivers, what is the prob. that least 1 doesn't signal when changing lanes? )1-(.2)^4 ) 1- (.8)^4
1- (.8)^4
Given a set of ordered pairs (x,y) so that sx=0.75, sy=1.6, r=.55. What is the slope of the least-squares regression line for this data? ) 1.82 ) 1.17 ) 2.18 ) 0.26 ) 0.78
1.17
The following is the distributions of number of cell phones per household in Lakeville (0,.1), (1, .1), (2,.25), (3,.3), (4, .2), (5, .5) ) 1.32 ) 1.7475 ) 2.5 ) .09 ) 2.9575
1.32
(0,.24) , (1,.37), (2, .20) , (3, .11), (4, .05), (5, .03) What is the expected value of the number of cars in a randomly selected household? ) 2.5 ) .1667 ) 1.45 )1 ) Cannot be determined
1.45
Test Score Mean: 100 Stand Dev: 15 Z-score is 1.20, what was the score on the test?
118
Mean age when women who had their first child: 27.3 Standard Dev: 5.4 Based on the empiracle rule; what ages are between 95% of the data ) 11.1 and 43.5 ) 16.5 - 38.1 ) 21.9 - 32.7 ) 21.9 - 38.1 ) 25 - 29.6
16.5 and 38.1
Mean 20 Standard Deviation .01 What is the minimum and maximum thickness of bolts that includes 95% of the population ) 19.98 - 20.02 ) 19.99 - 20.01 ) 19.97 - 20.03 ) 19.8 - 20.2 ) These cannot be accurately computed
19.98 - 20.02
Mean 20 Standard Deviation .01 What is the minimum and maximum thickness of bolts that includes 68% of the population ) 20 - 20.03 ) 19- 21 ) 19.98- 20.02 ) 19.99-20.01 ) 19.97- 20.03
19.99 - 20.01
People who have skin cancer : 896 People that did not use a tanning booth with skin cancer: 706 People with skin cancer that used a tanning booth: 190 Of the people in the study who had skin cancer, what fraction used a tanning booth?
190/896
Population H is a group of women with normally distributed heights. Population H has a population mean of 66 inches with a standard dev of 2.5 inches. What percentile is associated with z=-.68 ) 10th ) 25th ) 40th ) 50th ) 75th
25th
The SAT scores for applicants to a particular engineering school are normally distributed with a mean of 680 and a standard deviation of 35. Suppose that only applicants with scores above 700 are considered for admission. What percentage of the applicants considered have scores below 750? ) 2.3% ) 26.1% ) 71.6% ) 92% ) 97.7%
26.1%
Mean: 75 Standard Dev: 8 How much is 3.5 standard deviations from the mean?
28
Mean tickets purchased - 2.45 Each ticket costs 12 dollars What is the average spent on tickets? ) 2.45 ) 2.75 ) 24.50 ) 29.40 ) 36.00
29.40
The mean of a data set is 40 pounds with a standard deviation is 8 pounds. What corresponds to a z-score of -1.25 ) -30 ) -50 ) 30 ) 32 ) 50
30
A business stands to make 10,000 (prob. 15%), make 5,000(prob. 45%), break even (prob. 25%), or lose 5,000 (prob 15%) What is the expected profit in dollars ) 1500 ) 0 ) 3000 ) 3250 ) -1500
3000
Random digit table: 38683 50279 38224 09844 13578 12708 24684 5 samples ranging from 1-45. What represents her sample ) 38, 25, 02, 38, 22 ) 38, 68, 35, 02, 22 ) 38, 35, 27, 28, 08 ) 38, 65, 35, 02, 79 ) 38, 35, 02, 22, 40
38, 35, 02, 22, 40
The scores on a real estate licensing examination given in a particular state are normally distributed with a standard deviation of 70. What is the mean test score if 25% of the applicants scored above 475 ) 416 ) 428 ) 468 ) 522 ) Not enough information
428
Standard Dev 4 Mean 60 What is the max and min
48 and 72
Variance of X=16 Variance of Y=9 Z=X-Y // What is the standard deviation of Z
5
Using the empirical rule, what percent of the normal distribution lies outside 2 standard dev. of the mean? ) 0.3% ) 50% ) 5% ) 95% ) Can't be calculated
5%
A sample is taken of production per shift: 705, 700, 690, 705 the variance of the sample is approximately ) 8.66 ) 7.07 ) 75 ) 50 ) 20
50
Mean - 1.53 The dealer purchases the cars fr 21,000 and sells them for 24,500. What is the expected weekly profit from selling hybrid cars? ) 2380 ) 3500 ) 5355 ) 8109 ) 37485
5355
Population H is a group of women with normally distributed heights. Population H has a population mean of 66 inches with a standard dev of 2.5 inches In pop. H, what is the height of the 70th percentile? ) 63 ) 64.7 ) 66 ) 67 ) 67.3
67.3
The average weight of a newborn is 8 pounds with a standard deviation of 1.5 pounds. A baby has a weight at the 25th percentile Which of the following is the closest to the baby's weight? ) 2.00 ) 5.00 ) 7.00 ) 7.63 ) 8.90
7.00
F=(9/5)C+32 // Standard deviation of typical body temperature is .4 What would represent the standard deviation of typical body temperature in degrees F ) (9/5)(.4) +32 ) (9/5) (.4) ) (9/5) (.4) ^2 ) (9/5)^2 (.4) ) (9/5)^2 (.4)^2
9/5 (.4)
There is a doxplot that displays the daily high temperature, in degrees Fahrenheit, for a city in the southeastern United States during the 28 days in the month of February 2014. To say that there was a daiy high at 70 is saying that it was in the __ percentile ) 10 ) 25 ) 70 ) 90 ) 95
95
Linear equation was y=10 + .9x Y= Final Exam Score X= Score of the first test// Scored 95 ) 95 ) 85.5 ) 90 ) 95.5 ) None of the above
95.5
A study was conducted to evaluate the impact of taking a nutritional supplement on a person's reaction time. Volunteers were broken into three groups. These groups were randomly assigned to take either the supplement or the placebo. What is the best description for the study ) A randomized block design ) A completely randomized design ) A matched pairs design ) A randomized observational study ) A stratified observational study
A randomized block design
A residual: ) is the amount of variation explained by least-squares regression line of y on x ) is how much an observed y-value differs from a predicted y-value ) predicts how well x explains y ) is the total variation of the data points ) should be smaller than the mean of y
A residual is how much an observed y-value differs from a predicted y-value.
Why is the IQR considered to be a resistant statistic? ) Adding a new extreme observation has little effort on it ) Its equivalent to the distance from Q1 to the median, a resistant measure ) Adding an outlier changes the IQR dramatically ) It uses the mean in its calculation ) None of the above
Adding a new extreme observation has little effort on it
One college student read seven books The college median is equal to the high school median The mean is greater than the median in both groups
All are true
Which of the following statements concerning residuals from a LSRL is true? ) The sum of the residuals is always 0 ) A plot of the residuals is useful for assessing the fit of the least-squares regression line ) The value of a residual is the observed value of the response minus the value of the response that one would predict from the least-squares regression line ) An influential point on a scatter-plot is not necessarily the point with the largest residual ) All of the above
All of the above
What type of study was conducted to find measurements of water quality taken from a river downstream from an abandon chemical dumpsite. What type of study was conducted, and what is the response variable of the study?
An observational study was conducted, and the response variable was the concentration of the chemical in the water.
A company determines the mean and standard deviation of the number of sick days taken by its employees in one year. Which of the following is the best description of the standard deviation ) Approx. the mean distance between the number of sick days taken by individual employees and the mean number of sick days taken by all employees ) Approx. the median distance between the number of sick days taken by individual employees and the median number of sick days taken by all employees ) The distance between the greatest number of sick day taken by an employee and the mean number of sick days taken by all employees ) The # of days separating the fewest sick days taken and the most sick days taken when considering all employees )The # of days separating the fewest sick days taken and the most sick days taken when considering the middle 50% percent of the distribution
Approx. the mean distance between the number of sick days taken by individual employees and the mean number of sick days taken by all employees
30% of subscribers to cable television have to watch the shopping channel once a week. You must assign the digits of 0-9. What would prove to be an appropriate model ) Assign "0,1,2" as watching the shopping channel at least once a week and "3,4,5,6,7,8,9" as not watching ) Assign "0,1,2,3"as watching the shopping channel at least once a week and "4,5,6,7,8,9" as not watching ) Assign "1,2,3,4,5,"as watching the shopping channel at least once a week and "6,7,8,9,0" as not watching ) Assign "0" as watching the shopping channel at least once a week and "1,2,3,4,5" as not watching; ignore digits "6,7,8,9" ) Assign "3" as watching the shopping channel at least once a week and "0,1,2,4,5,6,7,8,9" as not watching
Assign "0,1,2" as watching the shopping channel at least once a week and "3,4,5,6,7,8,9" as not watching
n=20, xbar= 84.5, stardard dev=11.5, min - 68, Q1= 78, Med=86, Q3 = 91, Max = 112 What can be said about the number of outliers? ) 0 ) 1 ) 2 ) At least 1 ) At least 2
At least 1
A) Range - 6;; IQR - 2 ;; Not Symmetric B) Range - 6;; IQR - 2;; Symmetric Which of the following is incorrect? ) Ranges are the same ) IQR are the same ) Both sets are skewed to both lower and higher values ) Set A may not be symmetric ) Set A may have 100 times are many values as set B
Both Sets are skewed to both lower and higher values
Control groups are used in experiments in order to ) Control the effects of lurking variables such as the placebo effect ) Control the subjects of a study as to insure all participate equally ) Guarantee that someone other than the investigators, who have a vested interest in the outcome, control how the experiment is conducted ) Achieve a proper and uniform level of randomization ) None of the above
Control the effects of lurking variables such as the placebo effect
There is two types of pavement. There are 40 roads. A matched pair experiment is to be conducted. How would this be carried out?
Each of the 40 roadways is their own pair. Divide the roadways in half into half miles. Flip a coin to decide for each of the 40 roadways which half mile gets pavement
Variables: Family size, type of pet, grade of youngest child, family's average annual income over the past 5 years, dads occupation, mom's job status, phone number. What is categorical? ) Family, dad's occupation ) Dad's occupation, mom work? ) Grade of youngest ) Everything but average annual income and family size ) Everything but average annual income
Everything but annual income and family size
True or False: Voluntary response samples often under-represent people with strong opinions
False
Which of the following is true about the areas described under the normal curve? ) The area below the mean is greater than the area above the mean ) The area in the rage from z=0 - 1 is the same as the area in the range from z= 1 -2 ) Roughly 50% of the observations are located at the mean of the distribution ) Fewer than 1% of the cases are located three standard deviations above or below the mean. ) 95% of the observations have values twice that of the mean
Fewer than 1% of the cases are located 3 standard deviation above or below the mean.
Given that the median is 270 and the interquartile range is 20, which of the following statements is true? ) fifty percent of the data are greater than or equal to 270 ) Fifty percent of the data are between 260 and 280 ) Seventy-five percent of the data are less than or equal to 280 ) The mean is between 250 and 290 ) The standard dev is approximately 13.5
Fifty percent of the data are greater than or equal to 270
Using the regression equation above, correctly interpret the slope ) The effect of the crime rate on streetlights is given by the coefficient -.2 ) For every additional streetlight per block, the crimes per month go up by 2.4 ) For every additional streetlight per block, the crimes per month decrease by .2 ) For every additional crime per month, the number of streetlights goes down by .2 ) Every additional streetlight per block is associated with .2 more crimes a month, on average
For every additional streetlight per block, the crimes per month decrease by .2
The correlation between car weight and car reliability is -.3 The correlation between car weight and annual maintenance is .2 Which of the following statements are true? Heavier cars tend to be less reliable Heavier cars tend to cost more to maintain Car weight is related more strongly to reliability than to maintenance cost
Heavier cars tend to be less reliable Heavier cars tend to cost more to maintain Car weight is related more strongly to reliability than to maintenance cost
Box-plot about tropical storms Min - 0 Max - 60 Q1 - 10 Med - 50 Q3 - 55
High low, small middle, High High
Correlation of an AP Study is found to be .6 ) On average, a 40% increase in study time results in a 24% increase in exam score ) On average a 60% increase in study time results in a 100% increase in exam score ) 60% of a student's exam score can be explained by the # of study hours ) Sixty percent of the variation in exam scores can be accounted for by this linear regression model ) Higher exams scores tend to be associated with higher numbers of study hours
Higher exam scores tend to be associated with higher numbers of study hours
Which of the following statements is true for two events, each with a probability greater than 0? ) If the events are mutually exclusive, they must be independent ) If the events are independent, they must be mutually exclusive ) If the events are not mutually exclusive, they must be independent ) If the events are not independent, they must be mutually exclusive ) If the events are mutually exclusive, they cannot be independent
If the events are mutually exclusive, they cannot be independent.
Which of the following histograms is the mean less than the median?
Left Skewed (Left side small)
Which of the following can outliers affect significant? Mean, median, standard deviation, range, interquartile range. ) Mean, Standard Dev. Interquartile Range ) Median and Range ) Mean and Interquartile Range ) Mean, Standard Dev., Range ) None of the above
Mean, Standard Deviation, and Range
There is a four sided die numbered 1-4. At a time, there is one number laying facedown. Each number has a different value of points (1,0), (2,1), (3,0), (4,2) Consider two independent tossare are done. What is the probability of the sume of points of the two tosses
Must consist of all numbers, with scoring the highest being the least likely of all possibilities
An auto analyst is conducting a satisfaction survey. 2500 Ford, 2500 GM, 2500 Honda, and 2500 Toyota buyers. A sample of 400 is taken with 100 from each brand. Is this an example of a simple random sample: ) Yes, because each buyer was randomly sampled ) Yes their is a equal chance of buyer being sample ) Yes, their is equal representation ) No, every possible 400-buyer sample did not have an equal chance of being chosen ) No, pop. consisted of purchasers of 4 different brands of car
No, every possible 400-buyer sample did not have an equal chance of being chosen
Variables: Family size, type of pet, grade of youngest child, family's average annual income over the past 5 years, dads occupation, mom's job status, phone number. Which of the variables you collect are continuous data? ) Average annual income and phone number ) Only family size ) grade of youngest child and average annual income ) Only average annual income ) Average annual income and family
Only average annual income
Events D and E are independent, with P(D)= .6 and P(D and E)=.18 ) P(E) = .12 ) P(E) = .14 ) P(D or E) = .28 ) P(D or E) = .72 ) P(D or E) = .9
P(D or E) = .9
P(X) = 0.30 and P(Y) = 0.75 What must be true P(XnY) >= 0.05 P(XnY) >= 0.35 P(XnY) <= 0.30
P(XnY) >= 0.05 P(XnY) <= 0.30
Rainwater collected has a pH that ranges from 2.6 to 6.3 Which Box-plot is correct
Plot that ranges from 2.6 to 6.3 and has a mean of 4.5
Lauren is in a calculus class. She scored a 85 on both of her first 2 exams. The class mean for T1 was 75 with a standard deviation of 10 The class mean for T2 was 70 with a standard deviation of 15. Assuming normal distribution, on which exam did Lauren score better than the rest of the class ) She scored much better on the first exam ) She scored much better on the second exam ) She scored about equally well on both exams ) It is impossible to tell because the size is not given ) It is impossible to tell because the correlation between the two sets of exam scores is not given
She scored about equally on both exams
A company decide to randomly sample from their customer database as this includes phone numbers and addresses. This procedure is an example of which type of sampling ) Cluster ) Convenience ) Simple random ) Stratified ) Systematic
Simple Random
A bank wishes to survey 10 customers who have checking accounts, 10 with savings, and 10 who have checking and savings. What type of sampling is this ) Cluster ) Convenience ) Simple random ) Stratified ) Systematic
Stratified
Halle scores 600 on three tests Test 1: M=500// SD= 80 Test 2: M=470//SD= 120 Test 3: M=560//SD= 30 Rank her performance on each tests from best to worst?
Test 3, 1, 2
Which of the following random variables has a distribution which is most closely resembles a normal distribution? ) A random number between 0 and 9 from a table of single-digit random numbers ) The number of car accidents in 1 month at a very rural intersection ) The score of a student on a very easy 10 point quiz ) The annual income of a U.S. citizen ) The actual weight of a jar of peanut butter labeled 16 ounces
The actual weight of a jar of peanut butter labeled 16 ounces
Which of the following are true statements? The area under a normal curve is always equal to 1, no matter what the mean and standard dev are The smaller the standard dev of the normal curve, the higher and narrower the graph Normal curves with different means are centered around different numbers
The area under a normal curve is always equal to 1, no matter what the mean and standard dev are The smaller the standard dev of the normal curve, the higher and narrower the graph Normal curves with different means are centered around different numbers
Which of the following is correct? ) The correlation r is the slope of the least-squares regression line ) The square of the correlation is the slope of the least-squares regression line ) The square of the correlation is the proportion of the data lying on the least-squares regression line ) The coefficient of determination is the fraction of variability in y that can be explained by least-squares regression of y on x. ) The sum of the squared residuals from the least-squares line is 0.
The coefficient of determination is the fraction of variability in y that can be explained by least-squares regression of y on x.
Low - 72 , Q1 - 76 , Med - 77 , Q3 - 80 , Max - 94 Which of the following is true? ) Range is greater than 90 ) Interquartile range =22 ) The number of days that had at least 80 on-time arrivals is equal to the number of days that has the most 76 on-time arrivals ) The number of days that had from 76-80 on-time arrivals is equal to the number of days that has the most 76 on-time arrivals ) The diff. between the median and the lower quartile for the number of on-time arrivals is less than 2
The diff. between the median the lower quartile for the number of on-time arrivals is less than 2.
A scientist recorded the duration of the eruption of the Old Faithful geyser in Yellowstone National Park that occurred during a one-month time period. The histogram below shoes the distribution of the curation, in seconds of the eruptions? ) The distribution is uniform, is centered at about 200 second, and has a range of at most 250 seconds ) The distributions is skewed to the left, is centered at about 125, and has a range of at most 250 seconds ) The distributions is skewed to the right, is centered about 260 seconds, and has a range of at most 250 seconds ) The distribution displays two clusters, has a range of at most 200 seconds, and includes outliers below 75 seconds and above 325 seconds ) The distribution displays two clusters, with one cluster centered at about 125 seconds and the other centered at about 260 seconds, and has a range of at most 250 seconds
The distribution displays two clusters, with one cluster centered at about 125 seconds and the other centered at about 260 seconds, and has a range of at most 250 seconds
A set of data has a mean that is much larger than the median. Which of the following statements is most consistent with this info ) The distribution is symmetric ) The distribution is skewed left ) The distribution is skewed right ) The distribution is bimodal ) The data set probably has a few low outliers
The distribution is skewed right
An electrical company has a bid on two jobs. The owner believes - the prob of getting the first is .75 - the prob of getting the second is .5 - the prob of getting both jobs is .375 If the owner is correct which of these statements is true ) The events are both mutually exclusive and independent ) The events are mutually exclusive and are not independent ) The events are not mutually exclusive and are independent ) The events are neither mutually exclusive or independent ) The events are not mutually exclusive, and independence cannot be determined
The events are not mutually exclusive and are independent
Ms. Fisher wants to compare fertilizers and their effects on the growth of vegtables. The tests are performed on green beans. The new fertilizer is concluded to be more effective than that of the old. Why is this conclusion not appropriate?
The experiment only included green beans, so the results cannot be generalized to all vegetables
Staff want to obtain an estimate of the average numbers of years teachers in the state have been teaching. 50 teachers are randomly selected from a state conference. What is the sample and what is the population?
The sample is the 50 conference attendees, and the population is all teachers in the state.
Which of the following is a true statement about the correlation coefficient r? ) A correlation of .3 means that 30% of the points are highly correlated ) The square of the correlation measures the proportion f the y-variance that is predictable from a knowledge of x ) Perfect correlation is when the points lie exactly on a straight line, resulting in r=0 ) Multiplying every y-value by -1 leaves the correlation unchanged ) The unit of measurement for correlation is the y-unit per x-unit
The square of the correlation measures the proportion f the y-variance that is predictable from a knowledge of x
An AP Stat Teacher grades using z-scores. What does it mean when a student recieves a -1.3 z-score
The student scored 1.3 standard deviations lower on the second exam than the class average on the second exam
X - mean of 12.3/ standard dev. of .5 Y - mean of 9.1/ standard dev. of .3 ) MeanX - MeanY = 21.4 ) MedX - MedY= 3.2 ) RangeX - RangeY = 21.4 ) StandevX- StandevY= .8 ) VarX - VarY= .34
The variance of X-Y is .34
Which of the following is incorrect? The least square regression line equation is y=2000x + 1400 where y is the estimate raise and x is the performance rating. Which of the following statements is not correct ) For each increase of one point in performance rating, the raise will increase on average by 2000 ) This equation produces predicted raises with an average error of 0 ) A rating of 0 will yield a predicted raise of 1400 ) The correlation for the data is positive ) All of the above are true
This equation produces predicted raises with an average error of 0
Which of the following statements is true? Two events are mutually exclusive if they can't both occur at the same time Two events are independent if they have the same probability An event and its complement have probabilities that always add up to 1
Two events are mutually exclusive if they can't both occur at the same time An event and its complement have probabilities that always add up to 1
Patients are to be tested for an antidepressant. How can randomization be used for a randomized block design?
Within each block randomly pick half the patients to receive each antidepressant
A critical difference between experiments and observational studies is ...
an experiment often suggests a casual relationship, whereas and observational study only suggests an association
P(E)=0.34 and P(F) = .45 and P(EUF)= .637, the two events are ) independent and mutually exclusive ) independent, but not mutually exclusive ) mutually exclusive, but not independent ) neither independent nor mutually exclusive ) there is not enough information
independent, but not mutually exclusive
When drawing a histogram it is important to )label the vertical axis so the reader can determine the counts or percent in each class interval ) have a separate class interval for each observation to get the most informative plot ) make sure the heights of the bars exceeds the width of the class intervals so that the bars are rectangles ) leave gaps between bars. Leaving room for comments ) scale the vertical axis according to the variable whose distribution you are displaying.
label the vertical axis so the reader can determine the counts or percent in each class interval
100 volunteers suffer from anxiety take part in a study. 50 are selected to take the new drug. 50 are selected to take an existing drug. How would this be a double blind ) both drugs looked the same ) neither the subjects not the doctor knew which treatment any subject had received ) the doctor couldn't see the subjects and the subjects couldn't see the doctor ) there was a third group ) all of the above
neither the subjects not the doctor knew which treatment any subject had received
For testing a stain remover 40 families were split in half with 20 testing the new stain remover and 20 will use the company's current product. The most important reason for this random assignment is that ) randomization makes the analysis easier since the data can be collected and entered into the computer in any order ) randomization eliminates the impact of any confounding variables ) randomization is a good way to create two groups of 20 families that are similar as possible, except for the treatments they receive ) randomization ensures that the study is double-blind ) randomization reduces the impact of outliers
randomization is a good way to create two groups of 20 families that are similar as possible, except for the treatments they receive
An advantage to using surveys as opposed to experiments is that ) surveys are generally cheaper to conduct ) it is generally easier to conclude cause and effect from surveys ) surveys are generally not subject to bias ) surveys involve use of randomization ) surveys can make use of stratification
surveys are generally cheaper to conduct
If the standard deviation of a set is 0, you can conclude ) that there is no relationship between the observations ) that the average value is 0 ) that all observations are the same value ) that a mistake in arithmetic has been made ) none of the above
that all observations are the same value
