Currently patrons at the library speak at an average of 67 decibels. Will this average change after the installation of a new computer plug in station? After the plug in station was built, the librarian randomly recorded 64 people speaking at the library. Their average decibel level was 60.5 and their standard deviation was 17. 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 fail to reject accept the null hypothesis.
5. Thus, the final conclusion is that ...
   • The data suggest that the population mean decibal level has not significantly changed from 67 at = 0.01, so there is statistically insignificant evidence to conclude that the population mean decibel level at the library has changed since the plug in station was built.
   • The data suggest the populaton mean has significantly changed from 67 at = 0.01, so there is statistically significant evidence to conclude that the population mean decibel level at the library has changed since the plug in station was built.
   • The data suggest the population mean has not significantly changed from 67 at = 0.01, so there is statistically significant evidence to conclude that the population mean decibel level at the library has not changed since the plug in station was built.