A student wants to know how far above the ground the top of a leaning flagpole is. At high noon, when the sun is almost directly overhead, the shadow cast by the pole is 10 ft long. The student holds a plumb bob with a string 2 ft long up to the flagpole and determines that the point of the plumb bob touches the ground 15 in. from the base of the flagpole. How far above the ground is the top of the pole?