- Despite the voracious habits of army ants, mul- tiple species of invertebrates have managed to penetrate and exploit their societies. For exam- ple, the silverfish Malayatelura ponerophila is an insect that lives only in colonies of the South- east Asia army ant, Leptogenys distinguenda, where it steals food brought in by the ants. If detected, the silverfish becomes ant food (see photo on the next page), but how does it usually evade detection? Ants recognize other ants from their own colony with a chemical signature, a complex blend of cuticular hydrocarbons (CHCs) on the surface of their exoskeleton. The silverfish have been observed rubbing up against the ants,20 and isotope-labeling studies indicate that ant CHCs are transferred to the silverfish this way. Does chemical mimicry contribute to ant tolerance of silverfish? In one of a series of experiments, von Beeren et al. (2011) collected individual silverfish from ant colonies and iso- lated them for six days, after which most of the acquired CHCs had evaporated. The aggressive behavior of the ants toward these silverfish was then compared with behavior toward control silverfish not isolated for six days. The data below measure ant aggression toward the silver- fish on a scale from 0 to 1. Control: 0.04, 0.00, 0.22, 0.10, 0.11, 0.54. Isolated: 0.25, 1.00, 1.00, 0.42, 0.50, 1.00, 1.00, 1.00. Ant aggression index Ant aggre on index s 1.0- 0.8- 0.6 0.4- 0.2- 0.0 1.07 0.8- 0.6- 0.4- 0.2- 0.0- Control Control Treatment Treatment Isolated Isolated a. Two commonly used methods for presenting the results are shown in the accompanying figure (with standard error bars). Which method is superior? Why? b. Without transforming the data, apply an appropriate method to test whether the aggression index by ants toward silverfish was affected by isolation.

Using all 1991 birth records in the computerized national birth certificate registry compiled by the National Center for Health Statistics (NCHS), statisticians Traci Clemons and Marcello Pagano found that the birth weights of babies in the United States are not symmetric ("Are babies normal?" The American Statistician, Nov 1999, 53:4). However, they also found that when infants born outside of the "typical" 37-43 weeks and infants born to mothers with a history of diabetes are excluded, the birth weights of the remaining infants do follow a Normal model with mean p = 3432 g and standard deviation o = 482 g. The following questions refer to infants born from 37 to 43 weeks whose mothers did not have a history of diabetes. %3D Compute the z-score of an infant who weighs 2189 g. (Round your answer to two decimal places.) Approximately what fraction of infants would you expect to have birth weights between 2760 g and 4230 g? (Express your answer as a decimal, not a percent, and round to…

During the 2013 season, Major League Baseball took steps to speed up the play of baseball games in order to maintain fan interest. The average duration of a game from a sample of 60 games played during the summer of 2012 was 2 hours and 52 minutes. The average duration of a game from a sample of 50 games played during the summer of 2013 was 2 hours and 46 minutes. For the purposes of this question, let 2013 games be population 1.                                                                 1a. A research hypothesis was that the steps taken during the 2013 season would reduce the population mean duration of baseball games. Formulate null and alternative hypotheses.                      1b. What is the point estimate of the reduction in the mean duration of games during the 2003 season?

A random sample of 107 Langara students was obtained. Students were asked to report their primary method of transportation traveling to (and from) Langara to their residence. A cross-tabulation of gender and method of transportation is shown below. Method of Transportation Gender Drive Alone Transit Other Male 19 25 3 Female 22 25 13 litu tho otudont is female? Show