1. The problem statement, all variables and given/known data Calculate the diameter of a baby's head if there is a time delay of 96 microseconds between receiving pluses from either side of the skull and the speed of ultrasound can be assumed to be 1250m/s. 2. Relevant equations 3. The attempt at a solution The diameter of the baby’s head can be calculated using distance = speed x time where: Speed of ultrasound = 1250 m/s = 0.00125 m/ms Therefore: Distance (diameter) = 0.00125 x 96 =0.08625 m = 8.6 cm (1dp) Where am in going wrong? I'm advised to think about the echo factor the sound waves leaves the transducer reaches the skull and then has to travel back to the transducer. Please help!