Author: Anonymous

A quality improvement team at a clinic randomly selected 11 patients and recorded their wait times after implementing a new check-in system. Before the new check-in system, the mean wait time was 22 minutes, and the standard deviation was 8 minutes.  Here are the measurements for the wait times from the sample:       10,    15,   20,   17,   30,   25,   15,   12,   12,   15,   17 The type of graph being used to display wait times is called a [a]. The shape of the distribution of wait times is [b]. The team conducting the study want to estimate the mean wait time using the new check-in system using these 11 randomly selected wait times.  To do so, they should use a(n) [c].

A brewing company employee was interested how to improve corn yields.  There is reason to suspect that drying the seeds in a kiln before planting them might improve yield.  The employee had access to 9 small plots of land.  Because soil fertility might vary from plot to plot, he divided each plot in half and planted regular seed in one half and kiln-dried seed in the other (randomly deciding which kind of seed was planted in each half plot).  Following are the resulting data (yield is measured in pounds per acre). What experimental design is this? [design] The appropriate hypothesis test was performed on the above data and resulted in a p-value of 0.0704.  Using the 0.05 level of significance, the correct conclusion is [conclusion]. Plot Kiln-dried seed Regular seed Difference in yield 1 2009 1903 106 2 1915 1935 – 20 3 2011 1910 101 4 2463 2496 – 33 5 2122 2060 62 6 1482 1444 38 7 1542 1612 – 70 8 1443 1316 127 9 1535 1511 24  

Researchers took a random sample of 64 truck drivers and reported that they averaged 2,920 miles per week with a standard deviation of 72 miles.  What is the standard error of the sample mean? (Round your answer to the nearest whole number.)

For an exit poll of a recent ballot issue as to whether a county tax should be imposed to fund public transportation, 53.1% of those polled said ‘yes.’  Which of the following statistical inference procedures should be used to determine if the majority of the population approved of the tax?

Food additives, such as the plant-based extract tara gum, are used in industrial fool preparations as thickening agents to stabilize emulsions and create an impression of thickness and creaminess without adding extra calories.  The effect of tara gum on the viscosity (in millipascal-seconds, mPa.s) of fruit yogurt drinks was assessed for various concentrations of tara gum (in grams per 100 grams of drink, g/100g).  The findings are summarized in the following scatterplot. The relationship between the viscosity of the yogurt drink and concentration of the tara gum can be described as [a]. Which one of the following is the best guessed value of the correlation coefficient for the viscosity of the yogurt drink and concentration of the tara gum? [b]

Flight crews are exposed to more cosmic radiation than most people because of the time spent at high altitudes.  Fifty crew members of Xinjiang Airlines wore radiation detectors.  Investigators reported an average exposure of 219 mrems (millirems), with a margin of error of ± 9.7 mrems.  Which of the following is a correct interpretation of this statement?

Flight crews are exposed to more cosmic radiation than most people because of the time spent at high altitudes.  Fifty crew members of Xinjiang Airlines wore radiation detectors.  Investigators reported an average exposure of 219 mrems (millirems), with a margin of error of ± 9.7 mrems.  Which of the following is a correct interpretation of this statement?

A sociologist is studying where homeless children in a particular city spend most of their time.  The sociologist queried homeless children in one homeless shelter downtown to carry out the survey. The population of interest is [a]. The sample is [b].

Tree diameters are related to “growth rings” in trees and larger diameters are associated with taller trees. The scatter plot of a survey of 958 trees in an old-growth forest in Canada showed evidence of a linear relation between tree height (m) and diameter (cm).   The resulting least squares regression line equation  Height = 2.79 + 0.55× Diameter has an R2 value of 0.92. Which of the following is the slope of the least squares regression line equation?

An experiment investigated whether cell phone use changes drivers’ reaction times.  College students were randomly allocated to a cell phone group or a control group.  The experiment measures subjects’ response times (in milliseconds) in a driving simulation.  For the cell phone group, the sample mean time was 585.2, the sample standard deviation was 89.6, and the sample size was 32.  For the control group, the sample mean time was 533.7, the sample standard deviation was 65.3, and the sample size was 32. The null hypothesis is that the mean reaction times are equal. Which is the appropriate alternative hypothesis for this investigation?