How many electrons are in the upper level? Problem 2

Question

Problem 1 of chapter 6 of the course-pack. Use eqn. 2.27 for the definition of decibel.
Eqn. 2.27 : A(w)=-20log|T(jw)| db

Use the plot to calculate the repeater distance in a long haul optical communication system. Assume that a repeater is needed when the original signal has attenuated to 1% of its original value.
Do the calculations for laser wavelengths of 1) 1.55 µm 2) 1.2 µm 3) 1.8 µm
Note that intensity or energy is proportional to the square of the amplitude of the wave.