Xếp ngẫu nhiên 5 bạn An, Bình, Cường, Dũng, Đông ngồi vào một dãy 5 ghế thẳng hàng (mỗi bạn ngồi 1 ghế). Xác suất của biến cố “hai bạn An và Bình không ngồi cạnh nhau” là:

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Một số câu hỏi khác có thể bạn quan tâm.

• Cho . Chọn ngẫu nhiên số trong tập hợp . Tính xác suất để trong ba số được chọn không có hai số liên tiếp.

• Read the passage and choose the correct answer:
  Galileo Galilei, one of the first modern scientists, was born in Pisa, Italy, in 1564. About twenty years later he attended the University of Pisa. At first he studied philosophy, but later he studied mathematics and astronomy. He was interested in the way the earth and other planets move around the sun. He made the telescope, which made far-away things look larger and easier to examine. He also started the new way of working in science. Before Galileo; scientists did not do experiments. They just guessed about how something happened. Galileo was different. He did not just make guesses. He did experiments and watched to see what happened.
  Galileo was famous for his study of how things fall. He was the first person to do experiments about this problem. Before, people thought that heavy things always fell faster than light things. He found out that this was not true. He took a heavy ball and a light ball and he dropped them both from a high place. They fell at the same speed. This meant that weight is not important. This is the law of failing bodies. It is an important law for understanding our world.
  The life of the scientist was not always easy in the 1500s. For example, Galileo got into trouble because of his scientific ideas. His ideas were not the same as the religious ideas at the time. Many religious people did not agree with him. During his whole life he had to worry about this. He even went to prison for a while. But no one could stop him from thinking: He continued to look for scientific answers to his questions about the world.
  Question. In his study of how thin^gs fall. Galileo found out that
  
• Lợi ích chủ yếu của việc xây dựng đường hầm giao thông dưới biển Măng-sơ?
  

• It’s time you _________the house. It looks to dirty now.

• Tìm tất cả các giá trị thực của tham số để phương trình vô nghiệm.                                 

• Một mũi nhọn S chạm nhẹ vào mặt nước dao động điều hòa với tần số ƒ = 40 Hz. Người ta thấy rằng hai điểm A và B trên mặt nước cùng nằm trên phương truyền sóng cách nhau một khoảng d = 20 cm luôn dao động ngược pha nhau. Biết tốc độ truyền sóng nằm trong khoảng từ 3 m/s đến 5 m/s. Tốc độ đó là
  
  

• Một lò xo có độ cứng k = 100 N/m và chiều dài tự nhiên bằng 30 m. Nếu dùng một lực có độ lớn 3 N để nén dọc theo trục lò xo thì chiều dài của lò xo khi cân bằng là:

• If you ________ a book, you have a brief look at it without reading or studying it seriously.

• Đồ thị hàm số có bao nhiêu điểm cực trị?        

• I would rather she __________too much in the class yesterday.