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A researcher conducted a study to investigate the performance of students on an exam and their levels of anxiety.  An anxiety survey is given to students before the exam.  A higher score on the survey means the student experiences a higher level of anxiety.  The researcher claims that the correlation of -0.91 shows there is a strong causal relationship between anxiety and exam performance.  Explain what is wrong with this interpretation.

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.  Data were collected for both groups and the p-value for the appropriate hypothesis test was calculated to be 0.06.  Which of the following statements is correct?

A seller, who sells pet products within the United States, on Amazon wants to survey customer satisfaction.  Match the sampling design with the appropriate description.

Investigators took a random sample of 100 crew members of Xinjiang Airlines who wore radiation detectors and reported an average exposure of 219 mrems (millirems) of radiation with a standard deviation of 20 mrems.  What is the standard error of the sample mean?  (Round your answer to the nearest whole number.)

Refrigerators are usually fairly accurate, but the true temperature has some variability from what is stated on the thermometer inside.  A 95% confidence interval for the true temperature of a refrigerator thermometer set at 40°F is (35.50 and 41.25).  What is the margin of error?  (Round your answer to 2 decimal places.)

Environmentalists studying the effect of fire on the nutrients in soil measured the calcium level in randomly selected soil samples for 8 plots before and after a prescribed burn. Before the burn, the mean calcium level was 66.8 kg/plot, and the standard deviation was 14.65 kg/plot.  Here are the measurements for these plots after the burn:       9,    18,   36,   24,   18,   12,   25,   26  The type of graph being used to display calcium levels after the burn is called a [a]. The shape of the distribution of calcium levels after the burn is [b]. The environmentalists conducting the study want to estimate the mean calcium level after the burn using these eight randomly selected after-burn soil samples. To do so, they should use a(n) [c].

Is the following statement true or false?   If the Fed wishes to decrease the supply of money and credit, it may sell government securities, raise the discount rate, or lower required reserve ratios.

Is the following statement true or false?   If the Fed wishes to decrease the supply of money and credit, it may sell government securities, raise the discount rate, or lower required reserve ratios.

In response to the destructive bank panics of the Great Depression, future bank panics are designed to be prevented by

In response to the destructive bank panics of the Great Depression, future bank panics are designed to be prevented by