The silvery blue-green coloring of the Colorado spruce makes it a perfect Christmas tree. For a tree farmer in Indiana, when a seedling is planted, at time t = 0, the height of the tree is 1 foot. If h(t) is the height of the tree, in feet, at time t years after it is planted, then the rate of growth is proportional to the difference between its maximum height, 10 feet, and its current height and is