1-7 Energy and power of a traveling wave on a string

Energy is transmitted at an average rate of Pavg,1 by a wave of frequency f1 on a string with tension t1. What is the new average energy transmission rate Pavg,2 in terms of Pavg,1,

a.  if the tension of the string is increased to t2 = 4t1, and

b.  if, instead, the frequency of the wave is decreased to   f2 = f1/2?

Example 2