Do SAT coaching classes work? Do they help students to improve their test scores? Four students were selected randomly from all of the students that completed an SAT coaching class. For each student, we recorded their first SAT score (before the class) and their second SAT score (after the coaching class). d out of Student 1 3 question First SAT score 920 830 960 910 Second SAT score 1010 800 1000 980 To analyze this data, we should use Select one: O a. the one-sample f test. O b. the matched pairs ttest. c. the two-sample ftest. O d. Any of the above are valid. It just needs to be some type of t test since o is unknown. Clear my choice 2 DDT is a pesticide banned in the United States for its danger to humans and animals. In an experiment on the impact of DDT, six rats were exposed to DDT poisoning and six rats were not. For each rat in the experiment, a measurement of nerve sensitivity was recorded. The researchers suspected that the mean nerve sensitivity for rats exposed to DDT is greater than that for rats not oisoned. The data follow: jut of Poisoned rats: 12.207 16.869 25.050 22.429 8.456 20.589 Unpoisoned rats: 11.074 9.686 12.064 9.351 8.182 6.642 Let mu(1) be the mean nerve sensitivity for rats poisoned with DDT. Let mu(2) be the mean nerve sensitivity for rats not poisoned with DDT. Reference: Ref 17-4 The numerical value of the standard error of the difference in sample means is Select one: a. 4.05 O b. 2.71. O c. 1.30. O d. 9.02. Question 7 A sports writer wished to see if a football filled with helium travels farther, on average, than a football filled with air. To test this, the writer used 18 adult male volunteers. These volunteers were randomly divided into two groups of answered nine subjects each. Group 1 kicked a football filled with helium to the recommended pressure. Group 2 kicked a football filled Marked out of standard deviation s1 = 8 yards. The mean yardage for group 2 was in = 26 yards, with a standard deviation s2 = 6 yards. Assume the two groups of kicks are independent, Let us and inggroupwas * * 30 yards, with a pendent. Let it and py represent the mean yardage we would 1.0 observe for the entire population represented by the volunteers if all members of this population kicked, respectively, a helium- and an air-filled football. Assume that two-sample eprocedures are safe to use. Flag question Ret 17-2 Suppose the researcher had wished to test the hypotheses HO: MY = H2 Haith > H2. The Pvalue for the test is (use the conservative Option 2 for the degrees of freedom) Select one : O a. larger than 0.10. b. below 0.01. O c. between 0.05 and 0.01 O d. between 0.10 and 0.05. Question 8 Is there a difference in the amount of airborne bacteria between carpeted and uncarpeted rooms? In an experiment, five rooms were carpeted and five were left uncarpeted. The rooms are similar in size and function. After a Not yet suitable period of time, the concentration of bacteria in the air wa bacteria in the air was measured ( in units of bacteria per cubic foot) in all of these rooms. The data and summaries are provided: aswered Marked out of Carpeted rooms: 184 27.0 P Flag question Uncarpeted rooms: 172 17.9 Anforonce: Ref 17-3 Based on the analysis above f the following is a reasonable conclusion? Select one: O a. There is very little evidence (P 0.40) that the mean bacterial concentration in carpeted rooms is greater than that in uncarpeted rooms. O c. There is evidence (P 0.40) that the mean bacterial concentration in carpeted rooms is greater than that in uncarpeted rooms. Question 9 A psychologist has developed a set of activities which she hopes will help children develop better reading skills. In a study of the effectiveness of these activities, one class of second grade children learns with the activities. Another class of second grade children serves as the control and learned without the activities. After some period of time, the reading skills of all of these children were assessed on a scale of 0 to 100. A summary of these data Marked out of F Flag question Activities class: 51.48 11.01 No Activities class 15 41.52 17.15 Reference: Ref 17-1 Which of the following would lead us to believe he t-procedures were not safe to use here? Select one: O a. The sample medians roups were slightly different. O b. Some children lear could be outliers in the data. O c. The non-activity group om Normal with not a large sample size. O d. The two population distributions being studied are slightly non-Normal. Question 10 DDT is a pesticide banned in the United States for its danger to humans and animals. In an experiment on the impact of DDT, six rats were exposed to DDT poisoning and six rats were not. For each rat in the experiment, a measurement of nerve sensitivity was recorded. The researchers suspected that the mean nerve sensitivity for rats exposed to DDT is greater than that for rats not poisoned. The data follow: nswered Marked out of Poisoned rats: 12.207 16.869 25.050 22.429 8.456 20.589 Unpoisoned rats: 11.074 9.686 12.064 9.351 - 8.182 6.642 P Flag question Let mu(1) be the mean nerve sensitivity for rats poisoned with DDT. Let mu(2) be the mean nerve sensitivity for rats not poisoned with DDT. Which of the following is a reasonable conclusion? Select one: O a. There isn't much evidence to support a conclusion that the mean nerve sensitivity is greater in rats exposed to DDT than in rats not exposed to DDT. O b. There is fairly strong evidence to support a conclusion that the mean nerve sensitivity is greater in rats exposed to DDT than in rats not exposed to DDT. O c. There are outliers in these data, so we can't rely on the two-sample f test. O d. This test is unreliable because the populations sampled are heavily skewed