2 single pop mean question C and D are only wrong

Currently patrons at the library speak at an average of 62 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 63 people speaking at the library. Their average decibel level was 61.6 and their standard deviation was 9. What can be concluded at the the a = 0.01 level of significance? a. For this study, we should use t-test for a population mean b. The null and alternative hypotheses would be: HO: UVV = 62 H1 : H VY v v a f. Based on this, we should fail to reject vy the null hypothesis. g. Thus, the final conclusion is that The data suggest the population mean has not significantly decreased from 62 at a = 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 that the population mean decibal level has not significantly decreased from 62 at a = 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. O The data suggest the populaton mean has significantly decreased from 62 at a = 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