A quadratic function models the height, in feet, of a projectile above the ground in terms of the time, in seconds, after it is launched. The model indicates the projectile has an initial height of 6 feet above the ground and reaches its maximum height of 262 feet above the ground 4 seconds after being launched. Based on the model, what is the positive time, in seconds, when the projectile hits the ground? Round your answer to the nearest tenth.