A pipe open at both ends resonates at a fundamental frequency fopen. When one end is covered and the pipe is again made to resonate, the fundamental frequency is fclosed. Which of the following expressions describes how these two resonant frequencies compare?

1.) fclosed = (1/2) fopen

2.) fclosed = (3/2) fopen

3.) none of these

4.) fclosed = fopen

5.) fclosed = 2 fopen