Một bể nước có dung tích 1m3 nước. Người ta mở vòi cho nước chảy vào bể. Ban đầu bể cạn. Trong giờ đầu, vận tốc nước chảy vào bể là 1 lít/phút. Trong các giờ tiếp theo, vận tốc nước chảy giờ sau gấp đôi giờ trước. Hỏi sau khoảng thời gian bao lâu thì bể nước đầy ?         

Chia sẻ

Một số câu hỏi khác có thể bạn quan tâm.

• Choose the best answer for the following sentence:

  It was more than he could bear. He couldn’t bear it _____________.
   

• Choose the best answer for the following sentence:

  We were very much surprised. We were ___________ surprised.
  
  

• Choose the best answer for the following sentence:

  He doesn’t get up early on Sundays. He gets up ___________.
              

• Choose the best answer for the following sentence:

  The writer can’t see Aunt Lucy __________. He’s having breakfast.
   

• Choose the best answer for the following sentence:

  He was a friendly waiter. He spoke to the writer _____________.
   

• Choose the word that has the underlined part pronounced differently from the rest:

  weather                      friend                     when                     great

• Choose the best answer for the following sentence:

  ____________Santos meet David, he lost again.
   

• Choose the word that has the underlined part pronounced differently from the rest:

  learning                       heart                        turn                     serve

• Choose the word that has the underlined part pronounced differently from the rest:

  same                     sure                         sound                         best

• Choose the best answer for the following sentence:

  ______________ every industry in our modem world requires the work of engineers.