Physics Problem

Simon is in a hot air ballon directly above Zack(on the ground). Zach fires a bullet at the balloon. But hes not sure whether his bullet strikes the balloon on the way up or on the way down, but the time between the pistol firing and the balloon bursting is the same as the time between the balloon bursting and zach hearing the bursting of the balloon. The initial speed of the bullet was 1% greater than the speed of sound (344m/s). HOW WAS THE BALLOON WHEN IT BURST? Ignore air resistance.