There are 60 students in a class. First, select some students and investigate their learning situation. If the probability of each student being drawn is 16. (I
(i) Let * * choose n students, n60 = 16, ∴n= 10, that is, * * * choose 10 students ... (4 points)
(II) The histogram of frequency distribution from 2+4+x+ 1= 10, x=3 is as follows:
㈢。 X = 0.2× 5+0.4×15+0.3× 25+0.1× 35 = 18, so it is estimated that the average study time of this class is18 hours. ... (12 points)