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TS EAMCET · Maths · Probability

5 persons entered a lift cabin on the ground floor of a 7 floor house. Suppose that each of them independently and with equal probability can leave the cabin at any floor beginning with the first. The probability of all the 5 persons leaving the cabin at different floors, is

  1. A 3602401
  2. B 554
  3. C 518
  4. D 5!7!
Verified Solution

Answer & Solution

Correct Answer

(B) 554

Step-by-step Solution

Detailed explanation

The number of floors of the building except ground floor is 6. The number of ways that the five persons can leave 6 floors is 65. ∴ The total number of cases is 65. The number of ways that the five persons can leave in different floors is 6P5. ∴ Probability =6P565…