Then draw 10 people from Grade One and 9 people from Grade Two. There are seven people in senior three.
The proportion of students in Grade One, Grade Two and Grade Three is 10: 9: 7.
That is to say. The lottery probabilities of Grade One, Grade Two and Grade Three are all 1/3.
However, if you draw 26 people in each age group.
Then the probability of senior three is the greatest. After all, the numerator is 26, and the denominator of senior three is 2 10 (minimum. )
The landlord's mistake is that he didn't understand the meaning of the problem.