An open pipe has a piston inserted into one of its ends. A tuning fork with the frequency of 342 Hz is sounded at the open end of the pipe. At the same time the piston is set in motion along the length of the pipe. It is observed that the air column in the pipe resonates when its length is 241.1 mm and then again when it's length is 749.2 mm. Calculate the end correction for this pipe and give your answer in mm.

An open pipe has a piston inserted into one of its ends. A tuning fork with the frequency of 342 Hz is sounded at the open end of the pipe. At the same time the piston is set in motion along the length of the pipe. It is observed that the air column in the pipe resonates when its length is 241.1 mm and then again when it's length is 749.2 mm. Calculate the end correction for this pipe and give your answer in mm.