Messages arrive at a communications facility according to a Poisson process with rate 2 per hour. The facility has 2 channels, and an arriving message will either go to a free channel [to Channel2 if both channels are free), or be lost if both are busy. The processing time for a message has the c.d.f. F(:t') = 1:2, if U a: :1: r: 1, = [1, if :1: E U, = 1, if :1? 3 1, when the weather is 'good', and the c.d.f. F(:r) = 1 e'I if U r: I