A study was conducted in order to estimate , the mean number of weekly hours that U.S. adults use computers at home. Suppose a random sample of 81 U.S. adults gives a mean weekly computer usage time of 8.5 hours and that from prior studies, the population standard deviation is assumed to be = 3.6 hours. We are 95% confident that the mean number of weekly hours that U.S. adults use computers at home is: between 8.1 and 8.9. between 7.8 and 9.2. between 7.7 and 9.3. between 7.5 and 9.5. between 7.3 and 9.7