7. At 0C, a pipe with both ends open resonates with a 3rd harmonic of 1910 Hz. a. Calculate the speed of sound in air. b. What is the length of the pipe? C. If one end of the tube was closed, what would be the frequency of the new 3rd harmonic? d. Draw a sketch for the standing wave pattern of the 3rd Harmonic for when the pipe has both ends open and only one end open. 8. When two guitar strings are plucked alongside each other, a beat frequency of 7.0 Hz is heard. One of the strings is known to vibrate at 516.0 Hz. What are the two possible frequencies for the unknown string?