Solution: (1) Analysis data: the maximum value is 2400, and the minimum value is 1600, so the value range is 2400-1600 = 800;

(2) The total number is 8000, so the borrowing frequency of natural science books is 2000÷8000=0.25, corresponding to the fan-shaped statistical chart.

The central angle is 0.25× 360 = 90; Similarly, the borrowing frequency of literary books is 0.30, which is in the fan system.

The corresponding central angle in the plan view is108; The borrowing frequency of life encyclopedia books is 0.20,

The corresponding central angle in the fan-shaped statistical chart is 72; Frequency of borrowing financial books

Is 0.25, and the corresponding central angle in the fan chart is 90 degrees. (Fan diagram as shown)

(3) Since 10000×0.30 = 3000, if the city library buys 10000 copies of these four books, it is more appropriate to buy 3000 copies of "literature and art" books.