Ap physics waves- linear density?

To measure the acceleration due to gravity on a distant planet, an astronaut hangs a 0.075-kg ball from the end of a wire. The wire has a length of 1.5 m and a linear density of 3.1 10-4 kg/m. Using electronic equipment, the astronaut measures the time for a transverse pulse to travel the length of the wire and obtains a value of 0.055 s. The mass of the wire is negligible compared to the mass of the ball. Determine the acceleration due to gravity.