Between two book-ends in your study are displayed your five favourite puzzle books. If you decide to arrange the five books in every possible combination and moved just one book every minute, how long would it take you ?

A. 1 hour
B. 2 hours
C. 3 hours
D. 4 hours

• number of ways of arranging 5 books = 5 ! = 5 x 4 x 3 x 2 x 1 = 120.
  
  So, total time taken = 120 minutes = 2 hours.
• 11 years agoHelpfull: Yes(5) No(0)
• possible arrangements are 5*4*3*2*1= 120
  
  For making a new arrangement , two books are required to be moved.
  so total 120*2=240 mins which will take 240 min or 4 hours.
• 13 years agoHelpfull: Yes(4) No(13)