What is the average (arithmetic mean) height of the n people in a certain group?
(1) The average height of the $$\frac{n}{3}$$ tallest people n the group is 6 feet $$2\over{\frac{1}{2}}$$ inches, and the average height of the rest of the people n the group is 5 feet 10 inches.
(2) The sum of the heights of the n people is 178 feet 9 inches.