can some one give me answer to this question please?

 

Three things:

First, homework problems should be posted in the "Homework Help" section of this forum...

Second, your question has nothing to do with radio, nor communication.

Third, what have you done to attempt to solve this problem. You'll find many people willing to help you here, but not before you have attempted, and shown, a solution to the problem.

Until then, please enjoy this musical interlude by Ludwig von Beethoven, titled, "Silence"....