In some mining operations, a byproduct of the processing is mildly radioactive and release of these byproducts into the environment may contaminate the freshwater supply. There are strict regulations for the maximum allowable radioactivity in supplies of drinking water, namely an average of 5 picocuries per litre (pCi/L) or less. A random sample of 40 specimens of water from the city’s water supply gave a mean of 5.39 pCi/L and a standard deviation of 0.77 pCi/L. Is the city’s water supply contaminated? Test this hypothesis at the 0.01 level of significance. Give an approximate p-value for the test statistic.

In a certain article, laser therapy was discussed as a useful alternative to drugs in pain management of chronically ill patients. To measure pain threshold, a machine was used that delivered low-voltage direct current to different parts of the body (wrist, neck, and back). The machine measured current in milliamperes (mA). The pretreatment experimental group in the study had an average threshold of pain (pain was first detectable) at ? = 3.22 mA with standard deviation ? = 1.25 mA. Assume that the distribution of threshold pain, measured in milliamperes, is symmetric and more or less mound-shaped. (Round your answers to two decimal places.) (a) Use the empirical rule to estimate a range of milliamperes centered about the mean in which about 68% of the experimental group will have a threshold of painfrom  mA to  mA(b) Use the empirical rule to estimate a range of milliamperes centered about the mean in which about 95% of the experimental group will have a threshold of painfrom  mA to…

The toco toucan, the largest member of the toucan family, possesses the largest beak relative to body size of all birds. This exaggerated feature has received various interpretations, such as being a refined adaptation for feeding. However, the large surface area may also be an important mechanism for radiating heat (and hence cooling the bird) as outdoor temperature increases. Here are data for beak heat loss, as a percent of total body heat loss from all sources, at various temperatures in degrees Celsius. [Note: The numerical values in this problem have been modified for testing purposes.]   Temperature (oC)(oC) 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Percent heat loss from beak 33 32 33 32 39 43 56 48 44 49 44 56 58 60 60 63 The equation of the least-squares regression line for predicting beak heat loss, as a percent of total body heat loss from all sources, from temperature is: (Use decimal notation. Enter the values of the intercept and slope rounded to two…

An article reported data from a study in which both a baseline gasoline mixture and a reformulated gasoline were used. Consider the following observations on age (yr) and NOx emissions (g/kWh): Engine 1 2 3 4 5 6 7 8 9 10 Age 0 0 2 11 7 16 9 0 12 4 Baseline 1.70 4.38 4.06 1.24 5.29 0.59 3.35 3.45 0.73 1.22 Reformulated     1.86     5.91     5.51     2.70     6.50     0.71     4.95     4.86     0.72     1.41   Construct scatter plots of the baseline NOx emissions versus age.  What appears to be the nature of the relationship between these two variables? There is no compelling relationship between the data. As age increases, emissions also increase.     As age increases, emissions decrease.