Reclaimed phospate land in Polk County Florida has been found to emit a higher mean radiation level than other nonmining land in the county. Suppose that the radiation level for the reclaimed land has a distribution with mean 5.0 working levels (WL) and a standard deviation of 0.5 WL. Suppose further that 20 houses built on reclaimed land are randomly selected and the radiation level is measured in each.a. What is the probability that the sample mean for the 20 houses exceeds 4.7 WL?b. What is the probability that the sample mean is less than 4.8 WL?