The maximum fequency for reflection of sky waves from a certain layer bof the ionosphere is found to be `f_(max) =9(N_(max))^(1//2)`, Where N _max is the maximum electron density at that layer of the ionosphere.On a certain day it is observed that signals of frequencies higher than 5 MHz are not received by reflection from the `F_(1)` layer of the ionosphere while signals of frequencies higher than 8 MHz are not received by reflection from the `F_(2)` layer of the ionosphere. Estimate the maximum electron densities of the `F_(1)` and `F_(2)` layers on that day.