Two years ago, the average level of a certain noxious chemical at the mouth of the kentucky river was 180 parts per million. since then, new water treatment facilities have been added upstream and dumping regulations have been strictly enforced, leading to the belief that the average level of the pollutant has been reduced. to verify this belief, 49 random samples are taken at the mouth of the river. the mean and standard deviation of these samples are, respectively, 162 parts per million (ppm) and 42 ppm. what hypotheses would you test if you want to show that the mean level of this particular pollutant has been reduced? what is the value of the appropriate test statistic for verifying the belief? what is the p-value of the appropriate test for verifying the belief?

An electronics manufacturer wants to know if customers would be interested in a detachable keyboard for their tables and if so, what the most important features would be. the manufacturer partners with an electronics store to include copies of the survey with every purchase at that store for one week. which of the following best explains why this random sample is unlikely to be a good representative sample of tablet owners' preferences for a detachable keyboard? a) one week is likely not enough time to get a large enough sample. b) most people won't bother to send in the survey, which is likely to skew the results c) there is no way to verify whether the responders to the survey actually own a tablet d) the survey is biased because it was conducted through an electronics store, not the general population

Which graph represents an even function?

Aculture started with 3000 bacteria. after 5 hours it grew to 3900 bacteria. predict how many bacteria will be present after 9 hours