Solution: (1) Class size = 18÷45%=40 (people);

(2) The number of students is 0.5- 1h =40×30%= 12, as shown in the figure:

(3)*** There are 40 students, and the median time to finish homework is the average of the 20th number and the 2nd1number, that is, the median time is within 1- 1.5h;

(4) It is estimated that the number of ninth-grade students who have finished their homework more than 1.5h =8044×

4+6

40

=20 1 1 (person).