That is, the number of students who answered the questionnaire was 48;

(2)48×25%= 12 (person)

That is, the number of people who like the second method is 12.

Complete the statistical chart as follows:

.

(3) The proportion of people who like ① = 1648= 13,

Like the proportion of ② = 14,

The proportion of people you like ③ = 14,

Like the proportion of ④ =848= 16,

Then the favorite teaching method of the whole grade students is the fourth one.

The number of people who choose this method =420× 13= 120.

The fan-shaped central angle of people who like this method = 360× 13 = 120.