So the probability of a student being drawn is p = 1 10. (3 points)
(II) Question meaning X =1000-(60+90+300+160) = 390, (4 points)
Therefore, it is estimated that the number of students who have reached the excellent line in this middle school is m =160+390×120-1120-90 = 290 (people). (6 points)
(iii) Histogram of frequency distribution. (9 points)
The average math score of this school in this exam is. x = 60× 15+90×45+300×75+390× 105+ 160× 135 1000 = 90。 (65438
It is estimated that the average score of mathematics in this school is 90. ( 12)