Midterm Flashcards
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
A: True
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?
0.25; 0.06
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
False
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?
Approximately normal (sample sizes over 30)
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?
There are not enough random samples to determine this. The sample size must be 30 or larger.
36) This question refers to the dot plot below that has a population parameter of two. Which statement accurately describes this dot pot?
The dot plot has high variability and high bias.
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)
The mean is less than the median
Skewed left
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.
1 gap
Mean is greater than median
Skewed right
6) Which of the following are true for all normal density curves? Find all of the correct answers.
They are symmetric
The curve reaches its peak at the mean
The size of standard deviation impacts the height of the graph
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
75%
10) Taller people take less time to decorate a Christmas tree. In an experiment to study the decorating times of participants.
A
?) 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.
False?
?) 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?
79.1
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.
24.84
?) 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:
Unchanged; equal to 0.83
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?
The percentage of variable for air fare that is explained by flight length.
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?
Dependent variable which is SAT math score
16) Which of the following are true of least square regression lines? Find all of the correct answers.
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
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
10
42
29
10
37
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
Stratified;cluster
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?
Chance variation
?) 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.
Matched pair design
Randomly selected
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
Double blind
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?
No conclusion, bc no control group
