Currently patrons at the library speak at an average of 63 decibels. Will this average decline after the installation of a new computer plug in station? After the plug in station was built, the librarian randomly recorded 50 people speaking at the library. Their average decibel level was 57.1 and their standard deviation was 19. What can be concluded at the the = 0.01 level of significance?

1. For this study, we should use Select an answer z-test for a population proportion t-test for a population mean
2. The null and alternative hypotheses would be:

H0:H0: ? p Select an answer < > =

H1:H1: ? p Select an answer < > =

1. The test statistic ? t z = (please show your answer to 3 decimal places.)
2. The p-value = (Please show your answer to 4 decimal places.)
3. The p-value is ? >
4. Based on this, we should Select an answer reject accept fail to reject the null hypothesis.
5. Thus, the final conclusion is that ...
   • The data suggest that the population mean decibal level has not significantly decreased from 63 at = 0.01, so there is statistically insignificant evidence to conclude that the population mean decibel level at the library has decreased since the plug in station was built.
   • The data suggest the population mean has not significantly decreased from 63 at = 0.01, so there is statistically significant evidence to conclude that the population mean decibel level at the library has not decreased since the plug in station was built.
   • The data suggest the populaton mean has significantly decreased from 63 at = 0.01, so there is statistically significant evidence to conclude that the population mean decibel level at the library has decreased since the plug in station was built.