Class 7 (1) students in a school are divided into three groups to carry out math activities. 400 seventh-grade students like their favorite after-school life, and 300 eighth-grade students get pocket money. (1) According to the fan-shaped statistics, the proportion of seventh-grade students who like sports =1-25%-25%-10% = 40%.

Number of people who like sports =400×40%= 160 (people);

A: Among the 400 students in Grade 7, the one who likes sports best is 160.

(2) From the histogram of the eighth grade, it is concluded that the number of people purchasing study materials is = 300-100-75-25 =100;

(3) The average time for 300 ninth-grade students to finish their homework is = 50×1+80×1.5+120× 2+50× 2.5300 =10760 ≈1.

Answer: The average time for 300 students in Grade 9 to finish their homework is about 1.8 hours.