Questions
If the letters of the word 'REGULATIONS' are arranged at random, then the probability that there will be exactly 4 letters between R and E is
detailed solution
Correct option is D
Total number of ways of arranging 11 letters = (11)! ---------- (1) Selection of 4letters to be placed between R and E from the remaining 9 =9C4 These 4letters can be permuted in 4! ways. Now permutation of R and E can be interchanged in 2! ways. ∴ Number of favourable ways =9C46!2!------2 Hence, required probability =11! 9C46!2!Similar Questions
The odd against an event are 5 to 2 and the odds in favour of another disjoint event are 3 to 5. Then the probability that atleast one of the events will happen is
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