Stats Exam 78%

The heights of the trees in a forest are normally distributed, with a mean of 25 meters and a standard deviation of 6 meters. What is the probability that a randomly selected tree in the forest has a height greater than or equal to 37 meters? Use the portion of the standard normal table given to help answer the question. 0.13% 0.26% 2.3% 4.6%

2.3%

Priya is playing a game where she earns online badges for scoring higher than the mean score on a level. After the tenth level, she scores 3,540 points, which is 2 standard deviations above the mean score of 3,110 points. What is the standard deviation of scores for the tenth level? 215 311 354 430

215

The table below shows the average attendance of school events by the day of the week on which they are held.Average Attendance at School Events ThursdayFridaySchool Play300xBand Concert184250Which values of x will indicate an association between the two variables in the two-way table? Select the three correct answers. 250 304 407 422 714

250 304 407

Lee surveyed students at school about whether they buy lunch or bring lunch from home. The data she gathered is shown in the two-way table below.Source of Student Lunches Bring Lunchto SchoolBuy Lunchin the CafeteriaBoys1218Girls2030According to the data in the table, what percentage of boys bring lunch to school? 15% 37.5% 40% 66.7%

40%

Tiana compares the length of a name on a nameplate to the number of letters in the name. She draws the scatterplot below, and then she plots and determines an equation for the trend line.NameplatesBased on the information above, which is the best estimate of the number of letters that a name contains if the nameplate is 6 inches long? 3 4 10 12

3

Marleny is creating a game of chance for her family. She has 5 different colored marbles in a bag: blue, red, yellow, white, and black. She decided that blue is the winning color. If a player chooses any other color, they lose 2 points. How many points should the blue marble be worth for the game to be fair? 4 6 8 10

4

The equation of the trend line on the scatterplot below is . Using the trend line equation, what is the predicted approximate value of y when x = 3.5? 2.98 4.02 4.31 5.35

4.31

The graph below shows the hours students spent studying and their science test scores.Hours Spent Studying vs. Science Test ScoresA student gets a score of 70 on the test. Based on the trend line in the scatter plot, how much time did the student spend studying? 3.1 hours 4.5 hours 9.5 hours 40.5 hours

4.5 hours

A simple random sample of 50 adults was surveyed, and it was found that the mean amount of time that they spend surfing the Internet per day is 54.2 minutes, with a standard deviation of 14.0 minutes. What is the 99% confidence interval (z-score = 2.58) for the number of minutes that an adult spends surfing the Internet per day?Remember, the margin of error, ME, can be determined using the formula . 49.1 minutes to 59.3 minutes 50.3 minutes to 58.1 minutes 54.2 minutes to 58.1 minutes 54.2 minutes to 59.3 minutes

49.1 minutes to 59.3 minutes

The quadratic model f(x) = -5x2 + 200 represents the approximate height, in meters, of a ball x seconds after being dropped. The ball is 50 meters from the ground after about how many seconds? 2.45 3.16 5.48 7.07

5.48

What is the slope of the trend line drawn into the scatterplot?

15/163

Which table shows no correlation?

c

A survey of pet owners found that on average, they spend $1,225 annually per pet, with a standard deviation of $275. Between which two amounts would you expect 95% of the survey's respondents to spend annually per pet if the sample is approximately normal and comes from a normally distributed population? $675 and $1,500 $675 and $1,775 $950 and $1,500 $950 and $1,775

$675 and $1,775

Julia surveyed twenty households on her street to determine the average number of children living in each household. The tables below represent the collected data and a randomly selected sample from the population. Compare the mean of the population with the mean of the sample.Population Data03313222543330120233Sample Data53024What is the difference between the mean of the sample and the mean of the population? 0.55 1.25 2.25 2.80

0.55

Maria gathered the data in the table. She finds the line of best fit to be y = 2.78x - 4.4. What is the residual value when x = 4? -6.72 -0.58 0.58 6.72

0.58

Two students created a game of dice. They determined that each roll would add the value of the die if it was an odd number. If the roll was even, it would subtract the value of the die. (For example, a roll of 2 would subtract two points, but a roll of 3 would add three points.) What is the expected value for this game? -3 -0.5 0 0.5

-0.5

According to a survey, 15% of city workers take the bus to work. Donatella randomly surveys 10 workers. What is the probability that exactly 6 workers take the bus to work? Round the answer to the nearest thousandth. 0.001 0.002 0.128 0.899

0.001

The frequency table represents the results of a survey comparing the average age of household members to the way that they watch non-network television. Madigan converts the frequency table to a conditional relative frequency table by row. Television Viewing Method Which value should she use for X? Round to the nearest hundredth. 0.09 0.20 0.25 0.30

0.30

Which is most likely the correlation coefficient for the set of data shown? -0.872 -0.191 0.191 0.872

0.872

The relative frequency table shows the results of a survey in which parents were asked how much time their children spend playing outside and how much time they spend using electronics. Given that a child spends at least 1 hour per day outside, what is the probability, rounded to the nearest hundredth if necessary, that the child spends less than 1 hour per day on electronics? 0.22 0.25 0.70 0.88

0.88

The College Board states that the average math SAT score is 514 with a standard deviation of 117. Colleen gathered data from 50 students in her graduating class and found the average score to be 529. She thinks that her class's math SAT score is different from the average. Which of the following shows the correct z-statistic for this situation? 0.02 0.91 1.26 5.67

0.91

A company sells name plates for doors. An employee takes a random sample of name plates, measures the length of each name (in inches), and counts the number of letters in each name. She generates the scatterplot and trend line equation shown below. Name PlatesA customer would like the company to build him a name plate that is 22 inches long. What is the best estimate of the number of letters the company can have on the name plate? 9 10 12 39

12

The scores of a high school entrance exam are approximately normally distributed with a given mean = 82.4 and standard deviation = 3.3. What percentage of the scores are between 75.8 and 89? 68% 95% 99.7% 100%

95%

What does a residual value of 1.3 mean when referring to the line of best fit of a data set? A data point is 1.3 units above the line of best fit. A data point is 1.3 units below the line of best fit. The line of best fit has a slope of -1.3 The line of best fit has a slope of 1.3.

A data point is 1.3 units above the line of best fit.

Fiona asked her team to suggest ways of surveying the population of their middle school to find out how many students use bottled water.Which student has the method that is most representative of the school's population? Raina suggested that she ask everyone in her math class on Friday. Miya suggested that she ask students sitting in the first row of her classes on Friday. Ryo suggested that he ask the basketball players at his practice on Friday. Amir suggested that he ask every tenth student as he or she walks into school in the morning.

Amir suggested that he ask every tenth student as he or she walks into school in the morning.

The table of values below shows data for a five-word spelling test.Number of Letters vs. Percentage who Spelled CorrectlyWordNumber of letters in the wordPercentage of students who spelled the word correctly17482912357346595827Which describes how the data for word 2 should be plotted on a coordinate grid? From the origin, go 2 units to the right and 9 units up. From the origin, go 2 units to the right and 12 units up. From the origin, go 9 units to the right and 12 units up. From the origin, go 12 units to the right and 9 units up.

From the origin, go 2 units to the right and 12 units up.

The scatterplot below shows the shoe sizes of students and the number of books the students collected for the library book drive.Which statement about the scatterplot is true? In general, each student collected a number of books equal to his or her shoe size. In general, the shoe size of a student does not affect the number of books collected. As shoe size increases, the number of books collected decreases. As shoe size increases, the number of books collected increases.

In general, the shoe size of a student does not affect the number of books collected.

Rhonda manages wildlife samples for Ducks Unlimited. Two samples of duck populations at a migratory site are shown in the table below. Which statement about the samples is true?Duck Pond SamplesSample 1Sample 2Mallard19Mallard38Wood Duck3Wood Duck1Green Wing Teal10Green Wing Teal1American Widgeon8American Widgeon0 Rhonda needs to continue taking samples of ducks until both samples have at least one of each type of duck. Rhonda should take a third sample and then use the two that are most representative since these samples vary quite a bit. Rhonda should use both of these samples as they are to make inferences about the average population of each type of duck in the pond. Both samples must be biased because there are more Mallards than any other type of duck recorded in the sample.

Rhonda should use both of these samples as they are to make inferences about the average population of each type of duck in the pond.

Which of the following is a binomial experiment? Rolling a six-sided number cube 24 times and recording if a 4 comes up Rolling a six-sided number cube and recording the number until a 4 comes up Rolling a six-sided number cube and recording the number until an even number comes up Rolling a six-sided number cube 24 times and recording the number that comes up

Rolling a six-sided number cube 24 times and recording if a 4 comes up

Raj polled 100 students in his class to compare the number of hours that teen boys and girls played video games each week. The results of his survey are shown below. Which statement about his data sets is true?Hours of Video Game Time per Week for Teen BoysHours of Video Game Time per Week for Teen Girls The average boy plays 8.5 hours more per week than the average girl. The average boy plays 2 hours more per week than the average girl. The average boy plays the same amount of time per week as the average girl. The average boy plays 6 hours more per week than the average girl.

The average boy plays the same amount of time per week as the average girl.

The means and mean absolute deviations of monthly snowfall during the winter months in two cities are shown in the table below.Means and Mean Absolute Deviations ofSnowfall in North Town and South Town North TownSouth TownMean8.9 in.6.3 in.Mean Absolute Deviation0.55 in.0.48 in.The difference of the means is found and then compared to each of the mean absolute deviations. Which is true? The difference between the means is about equal to the mean absolute deviation of the data sets. The difference between the mean is about 2 times the mean absolute deviation of the data sets. The difference between the mean is about 4 times the mean absolute deviation of the data sets. The difference between the means is about 5 times the mean absolute deviation of the data sets.

The difference between the means is about 5 times the mean absolute deviation of the data sets.

The histogram below shows the number of properties in a town that sold within certain time periods. A bar graph entitled Number of Properties has Number of Days to Sell on the x-axis and number of properties on the y-axis, from 9 to 13. 11 properties took 1 to 30 days to sell; 10 properties took 31 to 60 days to sell; 12 properties took 61 to 91 days to sell. Why might the graph be considered misleading? The scales on the x- and y-axes are unequal. The interval on the x-axis is too large for the data set. The scale on the y-axis misrepresents the difference in the heights of the bars. The interval on the y-axis is too large for the data set.

The scale on the y-axis misrepresents the difference in the heights of the bars.

The box plots below show the ages of college students in different math courses. A box-and-whisker plot labeled Math 1 is shown. The number line goes from 16 to 22. The whiskers range from 17 to 21, and the box ranges from 18-20. A line divides the box at 19. A box-and-whisker plot labeled Math 2 is shown. The number line goes from 16 to 24. The whiskers range from 17 to 23, and the box ranges from 18-20. A line divides the box at 19. Math 1 Math 2 Which statement is true? The median age of the students in Math 1 is greater than the median age of the students in Math 2. The median age of the students is Math 1 is less than the median age of the students in Math 2. The mean and median age are most likely the same for both sets of data. The mean and median age are more likely to be the same for the students in Math 1.

The mean and median age are more likely to be the same for the students in Math 1.

LaTesha and Bernard are playing a game. Their scores for five games are shown in the table below.LaTesha's and Bernard's ScoresLaTesha's Scores9245673680Bernard's Scores6368626953Which statement comparing the means to the ranges is true? The means differ by 1, but the ranges differ by 40. The means differ by 1, but the ranges differ by 2. The means differ by 5, but the ranges differ by 40. The means differ by 5, but the ranges differ by 2.

The means differ by 1, but the ranges differ by 40.

A professor wants to determine information about the Internet usage of middle school students in one state. A sample of 500 boys and girls from middle schools across the state were asked, "How do you access the Internet when you are not at school?" Which best explains why the sample can be used to determine statistics that apply to the population? The sample represents the population. The sample is larger than the population. Each person in the population knows at least one person included in the sample. Each person in the sample has Internet access while they are not at school.

The sample represents the population.

The table shows the maze-completion times, in seconds, of two sets of mice in an experiment. Which statement is true about the variability of the group times? The times in Group A have a greater standard deviation. The times in Group A have a greater median. The times in Group B have a greater interquartile range. The times in Group B have a greater mean.

The times in Group A have a greater standard deviation.

Fiona recorded the mean math exam grade for six random samples of students from the entire seventh-grade class.SampleSample Mean Grade165292378445595670Why is a valid prediction for the mean of the population not possible using these samples? Fiona had too many samples. Fiona didn't have enough samples. The variation of Fiona's samples is too large. The variation of Fiona's samples is too small.

The variation of Fiona's samples is too large.

For which situations is it appropriate to use a sample? Select three options. What percentage of pick-up truck drivers want their next vehicle purchase to be another pick-up truck? What is the average number of rainbows each year in Honolulu? How many pedestrians would use a walkway built over a busy road? How many police cars are equipped with computers? What is the most popular car color in the teachers' parking lot?

What is the average number of rainbows each year in Honolulu? How many pedestrians would use a walkway built over a busy road? How many police cars are equipped with computers?

Administrators surveyed students enrolled in a new school in order to choose the school mascot. There are 480 students enrolled in the school. What is the proportion needed to calculate the average number of students that chose the lion for the mascot?

a

The scores of an eighth-grade math test have a normal distribution with a mean = 83 and a standard deviation = 5. If Din's test score was 92, which expression would she write to find the z-score of her test score?

a

Which survey is most likely affected by bias? a survey of teenagers about their favorite colors a survey of students about vacation policies in a school district a survey of supermarket shoppers about products they would like to see added a survey of bike riders on whether they wear helmets

a survey of students about vacation policies in a school district

Researchers compare the body composition of cattle feeding on a grain diet with that of cattle feeding on a grass diet. This method of gathering data is classified as a census. a sample survey. an experiment. an observational study.

an observational study.

Which of the following probabilities is the greatest for a standard normal distribution?

b

Which of the scatterplots have no correlation? Check all that apply.

c and d

Tatiana made a two-way table to describe what her friends like at the amusement park. Which could be the columns and rows for Tatiana's table? columns: likes roller coasters, likes water rides; rows: doesn't like roller coasters, doesn't like water rides columns: likes water rides, doesn't like roller coasters; rows: doesn't like water rides, likes roller coasters columns: likes roller coasters, doesn't like roller coasters; rows: likes water rides, doesn't like water rides columns: doesn't like water rides, likes roller coasters; rows: doesn't like roller coasters, likes water rides

columns: likes roller coasters, doesn't like roller coasters; rows: likes water rides, doesn't like water rides

Li designed a survey to determine how comfortable students at her middle school are with fractions. There are 600 students in her middle school. The students are equally distributed among grade levels. She selected a sample of 28 students in her first-period class. Which best explains Li's sample? random and biased random and unbiased nonrandom and biased nonrandom and unbiased

nonrandom and biased

Which relationships could have a negative correlation? Select three options. number of hours on video games and test scores speed of a car and minimum stopping distance average running speed and total race time adult's head circumference and age outside temperature and amount of a heating bill

number of hours on video games and test scores average running speed and total race time outside temperature and amount of a heating bill

The data in the table represent the height of an object over time. Which model best represents the data? quadratic, because the height of the object increases or decreases with a multiplicative rate of change quadratic, because the height increases and then decreases exponential, because the height of the object increases or decreases with a multiplicative rate of change exponential, because the height increases and then decreases

quadratic, because the height increases and then decreases

Saleem wants to compare the data in the four tables below. He graphs the data in each table and writes the rounded values for a, b, and r below each table, as shown.Table AMath Scores vs. Science ScoresTable BMath Scores vs. Science ScoresTable CMath Scores vs. Science ScoresTable DMath Scores vs. Science ScoresWhich set of data has the weakest association with its trend line? the data in table A the data in table B the data in table C the data in table D

the data in table A

David is a statistician. He has a sample size of 40 (which he cannot change). What element of his hypothesis test can he adjust to minimize the probability that he incorrectly rejects the null hypothesis? the mean of the population the mean of the sample the standard deviation of the population the significance level of the test

the significance level of the test