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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 ?
Answer & Solution
Correct Answer:
Option
B
Clearly, 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.
So, total time taken = 120 minutes = 2 hours.
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LoginThere is one more possibility of having the two end books either in bottom and top or vice-versa.So total 240 ways, i.e., 4hr