A study was conducted in order to estimate μ, 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 σ = 3.6 hours. Based on this information, what would be the point estimate for μ ?

a. 2.36
b. 8.5
c. 81
d. 3.6