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1. There are five comics numbered from 1 to 5. In how many ways can they be arranged, so that part-1 and part-3 are never together?
The total number of ways in which part-1 and part-3 are always together:
= 4! × 2!
= 48
Therefore, the total number of arrangements, in which they are not together is:
= 120 - 48
= 72
Solution:
The total number of ways in which 5 part can be arranged =5! =120.The total number of ways in which part-1 and part-3 are always together:
= 4! × 2!
= 48
Therefore, the total number of arrangements, in which they are not together is:
= 120 - 48
= 72