So I'm studying for my Physics exam tommorow and the damned Sound unit seems to always give me problems. Anyway I'm doing a review question relating to Beat Frequency and I just can't seem to figure out what to do. Here is the question and my sad attempt at it. When a violin string is sounded together with a pitch pipe having a frequency of 256 Hz, 21 beats are heard in 3.00s. If the string is tightend, the beat frequency increases (not sure why this sentence is here or it's purpose). What is the original frequency of the violin string? Well the first thing I did was calculate the Beat Frequency using the formula: Beat Frequency = # of beats / time Fb = 21 / 3s Fb = 7Hz I then proceeded to frequency of the violin string by doing this: Frequency of violin = Frequency of pitch pipe +/- Fb Fv = 256 Hz +/- 7Hz Fv = 263 Hz or 249 Hz To my knowledge those are the possible frequencies of the violin, but it's asking for the original frequency and I have no clue what to do. Any help would be greatly appreciated. Thanks.