Midterm

Question 1

37) When determining if the sampling distribution will be approximately normal, a researcher needs to find at least 10 successes and 10 failures for the shape to be approximately normal.

A: True
B: False

Answer 1

A: True

Question 2

38) A researcher takes a simple random sample of 50 female cats from the population of cats in a shelter in Fort Worth to see what proportion sampled have been sprayed prior to arrival at the shelter. Suppose that 25% of female cats are sprayed. What are the mean and standard deviation of the sampling distribution?

Answer 2

0.25; 0.06

Question 3

39) if you have fewer than 10 expected successes per sample, then we would expect a left skewed sampling distribution. If you have fewer than 10 expected failures per sample, then we would expect a right skewed sampling distribution. True or False

Answer 3

False

Question 4

40) 70% of first time customers who order a low carbohydrate meal and 60% of the first time customers who order a gluten-free meal will order again. The company takes separate random samples of 40 first time customers who order each kind of meal care. What is the shape of the sampling distribution for the difference in the sample proportions?

Answer 4

Approximately normal (sample sizes over 30)

Question 5

35) A delivery service tests the time it takes to deliver a meal within 10 mile radius of the store. The delivery times are normally distributed with a mean of 25 minutes and a standard deviation of three minutes. Suppose the delivery service test a random sample of three deliveries in Calculator the sample need of delivery time. What will be the shape of the sampling distribution?

Answer 5

There are not enough random samples to determine this. The sample size must be 30 or larger.

Question 6

36) This question refers to the dot plot below that has a population parameter of two. Which statement accurately describes this dot pot?

Answer 6

The dot plot has high variability and high bias.

Question 7

1) A five number summary (min, Q1, median, Q3, max) for a set of data is (3, 22, 35, 30, 45). Which of the following are most likely true about this data set. (Find all the correct answers)

Answer 7

The mean is less than the median
Skewed left

Question 8

2) This question refers to the following histogram about the travel time to school for 50 elementary students. Which of the following are true about this histogram? Find all of the correct answers.

Answer 8

1 gap
Mean is greater than median
Skewed right

Question 9

6) Which of the following are true for all normal density curves? Find all of the correct answers.

Answer 9

They are symmetric
The curve reaches its peak at the mean
The size of standard deviation impacts the height of the graph

Question 10

7) A statistics teacher gives the class a test. The time it takes to complete the test is approximately normally distributed with a mean of 42 minutes and a standard deviation of 11.9 minutes. Approximately what proportion of their response time is less than 50 minutes

Answer 10

75%

Question 11

10) Taller people take less time to decorate a Christmas tree. In an experiment to study the decorating times of participants.

Answer 11

A

Question 12

?) this question refers to the table below. The conditional distribution of juniors addressed for spirit week is greater than the marginal distribution of seniors. True or false.

Answer 12

False?

Question 13

?) In a history class, a linear equation equation was used to predict the final exam score based on the score on the first test. The equation was Y = 5+0.95X. Y is the final exam score and X is the score on the first test. STEPHANIE scored a 78 on the first test. What is the predicted value of her score on the final exam, rounded to the nearest 10th?

Answer 13

79.1

Question 14

11) In an economics class, a linear regression equation was used to predict the final exam score based on the score on the first test. The equation was y=4+0.87x where y is the final exam score and x is the score on the first test. Calvin scored a 68 on the first test and 88 on the final exam. What is the value of his residual, rounded to the nearest hundredth.

Answer 14

24.84

Question 15

?) The correlation between practice times and race times for running a distance race is r=0.83. IF the practice times were measured in miles and the race times were measured in kilometers (1 mile = 1.60934km), the correlation between practice times and race times would be:

Answer 15

Unchanged; equal to 0.83

Question 16

14) This question refers to the following computer output that predicts air fare for an air fare for an airlines flights from Dallas to 15 different cities from the flights length in miles. What does the R-Sq number represent?

Answer 16

The percentage of variable for air fare that is explained by flight length.

Question 17

15) This question refers to the following scatter plot and regression line to study if GPA predicts SAT Math scores. Which variable will be on the y-axis?

Answer 17

Dependent variable which is SAT math score

Question 18

16) Which of the following are true of least square regression lines? Find all of the correct answers.

Answer 18

Another name for least square regression lines is the line of best fit
The least square regression line is found by minimizing the sum of the squared residuals
The y-intercept of the regression line may not also make sense in the context of the problem
The least square regression line is found by inputting the residual values into the calculator
The least square regression line is found by comparing the z-scores of the data points

Question 19

17) We wish to draw a sample of 5 without replacement from a population of 60 students. Suppose the students are numbered 01,02,…,60, and the relevant line of the random number table is 1086422910374051623428356. Then the students selected are

Answer 19

10
42
29
10
37

Question 20

18) An airline conducts two different studies. The airline has 12 daily flights from Dallas to Miami. The first customer satisfaction survey is given to a random sample of 50 passengers from each flight on a single day. For the second

Answer 20

Stratified;cluster

Question 21

19) Sally, a hairdresser at Sophisticated Salon, sends out a questionnaire to 30 randomly selected customers who have purchased a product or service at the salon in the last three months. The questionnaire asked customer to rank their favorite products or services at the salon. Harriet, the cashier, decided to conduct the same study and received different results. Which of the following statement about this questionnaire is true?

Answer 21

Chance variation

Question 22

?) A track coach wants test the effectiveness of new styles of shoes for long distance runners. He selects the two fastest runners, and using a coin flip, randomly chooses wear the acics brand the other one to wear the Brooks brand. Can you repeat this process with all of his runners, choosing the two fastest remaining each type, he then compares the race times within each group of runners. Which statements are true of this experiment? Find all of the correct answers.

Answer 22

Matched pair design
Randomly selected

Question 23

22) In a famous study of factory workers and effective like in on productivity, the workers were aware of the survey and researchers discovered that worker productivity increases as the lighting changed, regardless of whether cop writer or darker and then work areas. What would have been the best improvement in the experiment design

Answer 23

Double blind

Question 24

23) A new COVID-19 vaccine was given to a group of 25 subjects. Six months after injection, 20 of the subjects reported tat they did not get COVID-19. From this information what is the best conclusion?

Answer 24

No conclusion, bc no control group

Question 25

24) what is the best way a researcher can improve the accuracy of the sample?

Answer 25

Larger sample size

Question 26

29) This question refers to the following Venn Diagram that showed the number of shared words in lyrics by 3 famous French singers, Booba, Nickfeu, and Brassens. (Find all the correct answers)

• The probability that a randomly selected word appeared in the songs by all three singers was .0156
• The probability that a randomly selected word appeared in the songs by all three singers was .908
• The probability that a randomly selected word appeared in the songs by Booba and Nekfeu, but not Brassens, was less than the probability that a randomly selected word appeared in songs by Nekfeu and Brassens, but not Booba
• The probability that a randomly selected word appeared in songs by only Brassens was less likely than if by only Nekfeu

Answer 26

A and D

Question 27

!!25) there is an 11% probability that wedding guests will have an allergy that the cook will need to accommodate. One day, a bridal party of 18 went to the restaurant for the rehearsal dinner. Assuming that each of the 18 customers is equally likely to need a special meal, what is the probability that at least one allergy free meal was requested?

Answer 27

87.7%

Question 28

21) A survey is administered to recent graduates from the ROTC training program at LISD high schools to compare a GPA of males and females. For a random sample of graduates, three variables are collected: sex GPA and home campus. Which statements are true of the study? Find all of the correct answers

Answer 28

Make inferences abt ROTC in the district
No cause and effect relationship
Too many confounding variables

Question 29

26) miss Brown teaches world history. She likes all students to participate in discussions so she can write each students name on an identical slip of paper and select students at random to contribute their thoughts. The chart below summarizes the grade level count for her class. If Miss Brown selects different students without replacing means between selections, what is the probability that both students are 10th graders?

Answer 29

0.048

Question 30

28) this question refers to the following dot plot. Each sample consists of successful free-throw attempts out of 12 made by the MVP on the girls basketball team. What is the probability that the MVP will make less than 10 free throws? Enter your answer to the nearest hundred.

Answer 30

0.2

Question 31

27) mr. “HERNANDEZ, the high school theater Director, is looking to recruit more upperclassman for the spring musical. The chart below summarizes the juniors and seniors related to participation in choir. Which of the statements below accurately describes the student population? Find all of the correct answers

Being a junior and in choir are mutually exclusive events
Being a senior and not being in choir are not mutually exclusive events
The probability that a randomly selected student from the student population is a not a junior or a senior and in choir is less than 1%
The probability that a randomly selected student from the student population is in choir or a junior is greater than the proper abilities at the selected student is a senior and is in choir

Answer 31

BCD

Question 32

A set of physics exam scores are normally distributed with a mean of 81 and standard deviation of 5 points. Find P(X<70). Round your answer to two decimal places.

Answer 32

.01390

Question 33

Double Roulette involves a spinning ball on a wheel with 38 numbered slots (0, 00, and 1 through 36). The goal is to bet whether the ball will land on a number or set of numbers. If the ball lands on your number or numbers, you win. For example, if you bet that the ball will land on an odd number, and the ball lands on 17, you win. If it lands on 20, you lose. You can choose on number, or various combinations of numbers for the best. You bet on numbers 3-18. What’s the likelihood of winning after one trial and what is the likelihood of winning both trials?

Answer 33

.42, .18

Question 34

33) A set of geometry exam scores are normally distributed with a mean of 75 points and a standard deviation of eight points. Find P when X is greater than 88. Round your answer to two decimal points.

Answer 34

0.0521

Question 35

31) your brother and sister each have a job at different stores with different management. Your sister‘s average weekly salary is $323 with a standard deviation of $22. Your brothers average weekly salary is $157 with a standard deviation of eight dollars. Find average weekly salary of your siblings combined and the standard deviation of their combined salaries.

Answer 35

$480; $23.41

Question 36

32) A bag of M&Ms has six colors, with a proportionately of each one bearing. The proportion of orange M&Ms is 20%. If you eat them one by one the probability of eating your first orange candy on or before your fourth pick is?

Answer 36

0.5904