Question 9: How to write multiple-choice questions in high school mathematics? Detailed process

Method 1:

This problem is the probability of equally possible events. The event involved in the experiment is that five books are randomly placed on a bookshelf, and one (5

5) As a result, the events that meet the conditions are that the books of the same subject are not adjacent, and * * * has C( 1

2) a (2

2) a (3

3) Find the probability of the three results.

From the meaning of the problem, we know that the problem is the probability of an equal possible event.

The event involved in the experiment is that five books are randomly placed on a shelf.

5)= 120 result,

Under the classification, the number of non-adjacent species of the same kind was studied.

Assuming that the first book is a Chinese book (or a math book) and the second book is a math book (or a Chinese book), there are 4×2×2×2× 1=32 possibilities;

Assuming that the first book is a Chinese book (or a math book) and the second book is a physics book, there are 8 possibilities: 4×12×1×1=;

Assuming that the first book is a physics book, there are1× 4× 2×1×1= 8 possibilities.

The probability that books on the same subject are not adjacent P=

48/ 120=2/5,

Method 2:

Can be solved from the opposite side

Two mathematics are adjacent, and two languages are also adjacent. There is a (2

2) a (2

2) a (3

3)=24 species

Two mathematics are adjacent, and two languages are not * * * A(2

2)C( 1