Solution: (1) 800 < 2,500 < 4,000,2,500 yuan is taxed according to the second method.

(2500-800)× 14%,

= 1700× 14%,

=238 yuan.

(2) Taxable amount of 5600 yuan:

5600× 1 1%,

=6 16 (yuan);

(3) The tax payable is 4,000 yuan: (4,000-800) ×14% = 448 yuan;

336 < 448, so it is the second way to pay taxes;

336÷ 14%+800=3200 (yuan).

(4) 7 15 > 448, so pay taxes according to the third method.

715 ÷11%= 6500 yuan