Mathematics
NULL
Medium
Question
10 books are placed at random on a shelf. The probability that a particular pair of books will always be together is _________?
A
1/10
B
2/5
C
1/5
✓ Official correct answer
D
1/2
Community credibility
Registered members can vote for the answer they believe is correct today and explain why. If the facts change after an election or news event, suggest a new option so others can vote it up.
A
1/10
No member explanations yet for this option.
B
2/5
No member explanations yet for this option.
C
1/5
No member explanations yet for this option.
D
1/2
No member explanations yet for this option.
Explanation
Treat the pair as one unit: (2 × 9!)/10! = 1/5.