4.b The post-lunch dip is the drop in mental alertness after a midday meal. Does an extract of the leaves of ginkgo tree reduce the post-lunch dip? To find out, 39 healthy participants aged 18 to 40...

Extracted text: 4.b The post-lunch dip is the drop in mental alertness after a midday meal. Does an extract of the leaves of ginkgo tree reduce the post-lunch dip? To find out, 39 healthy participants aged 18 to 40 were randomly assigned to two groups: to take either ginkgo extract or placebo. After lunch, each person was asked to read seven pages of random letters and to place an X over every e. The average number of misses per line was recorded for each person. After analyzing the sample data, the decision has been made to perform the pooled t-test to compare the population means. Which of the provided R outputs has led to the decision to perform the pooled t-test? sd Ginkgo 0.06383 0.01462 21 Placebo 0.05342 0.01549 18 mean sd Ginkgo 0.06431 0.02412 21 Placebo 0.05349 0.01112 18 mean n
F) 1 2.3366 0.1295 100 group > leveneTest(area Levene's Test for Homogeneity of Variance (center miles, data=Miles, center="mean"); "mean") Df F value Pr(>F) group 1 4.6355 0.03372 * 100 "/>
Extracted text: In each scenario, a decision has been made to use pooled or general t-test for comparing the two population means. For each scenario, decide which of the provided R outputs must have led to the decision of using a pooled or unpooled t-test. Question 4 Subquestions 4.a Does the population mean number of miles driven annually by the population of drivers who report living in rural areas (total per year, averaged per driver) differ from the population mean number of miles driven annually by the population of all drivers who report living in urban areas? To address this question, a random sample of 41 drivers living in rural areas was selected, and another random sample of 61 drivers living in urban areas was selected. After analyzing the sample data, the decision has been made to perform the general (unpooled) t-test to compare the population means. Which of the provided R outputs would have led to the decision to perform the general (unpooled) t-test? > leveneTest(area ~ Levene's Test for Homogeneity of variance (center = "mean") miles, data=Miles, center="mean"); Df F value Pr(>F) 1 2.3366 0.1295 100 group > leveneTest(area Levene's Test for Homogeneity of Variance (center miles, data=Miles, center="mean"); "mean") Df F value Pr(>F) group 1 4.6355 0.03372 * 100