1. The problem statement, all variables and given/known data In a certain binary-star system, each star has the same mass which is 7.5 times of that of the Sun, and they revolve about their center of mass. The distance between them is the 7.5 times the distance between Earth and the Sun. What is their period of revolution in years? 2. Relevant equations T2=(4∏2/(GM))r3 3. The attempt at a solution multiplied mass of sun by 7.5 to get M, multiplied 1 amu by 7.5 to get r T2=(4∏2/(6.67E-11)(1.491E31))x(1.125E12)3 T=2.38E8 seconds changed this to years and got 7.54 years but this was the wrong answer. Can anyone point out what I'm doing wrong? Thank you!