When meteorites falling to the ground high-speed passes through our atmosphere, the meteorite surface with the momentum of high temperature combustion air friction and volatile, experiments show that meteorites volatilization rate (i.e., reduce the rate of volume) is proportional to the meteorite surface area, the existing quality of a meteorite is uniform spheres, and always keep the ball in the process of falling. If it loses 7/8 percent of its volume in the 3s before it enters the atmosphere and starts burning up, how long will it take for the meteorite to completely burn up?