Paragraph: There are five students S 1 ,   S 2 ,   S 3 ,   S 4 and S 5 in a music class and…

Paragraph: There are five students S1, S2, S3, S4 and S5 in a music class and for them there are five seats R1, R2, R3, R4 and R5 arranged in a row, where initially the seat Ri is allotted to the student Si, i = 1,2,3,4,5. But, on the examination day, the five students are randomly allotted the five seats
Question : The probability that, on the examination day, the student S1 gets the previously allotted seat R1, and NONE of the remaining students gets the seat previously allotted to him/her is
  1. 340
  2. 18
  3. 740
  4. 15

Solution

Required probability =4!12!-13!+14!5!=9120=340

Asked in: JEE Advanced 2018 (Paper 1)

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