1. The problem statement, all variables and given/known data 2. Relevant equations fb=f2-f1 or f1-f2 3. The attempt at a solution Well, i know how to calculate the beat difference, but I do not under stand which of the 303Hz or the 297Hz referred to question #4 are the correct initial frequencies before adding the Plasticine!!! Can some one explain that to me please! Thank you for your time.