As a hot-air balloon rises vertically, its angle of elevation from a point P on level ground 110 kilometers from the point Q directly underneath the balloon changes from 16 .888 to 33 .16667 (see the figure). Approximately how far does the balloon rise during this period? Round the answer to the nearest tenth of a kilometer.
Please enter your answer as a number without the units.
Please enter your answer as a number without the units.