in Education by
The numbers 1,2,3,.., n are arranged in a random order. The probability that the digits 1,2,3,..,k(n>k) appears as neighbours in that order is A. (n-k)! n! B. n-k+1 .nCk C. n-k .nCk D. k! n! Select the correct answer from above options

1 Answer

0 votes
by
 
Best answer
Correct Answer - B The numbers 1,2,3,..n, can be arranged in a row in n! ways. The total number of ways in which the digits 1,2,3,..,k(k<n) occur together is k!(n-k+1)! Hence, required probability = k!(n-k+1)! n! = n-k+1 .nCk

Related questions

0 votes
0 votes
    The digits 1,2,3,4,5,6,7,8 and 9 are written in random order to form a nine digit number. The probability that this ... 2 9 2 D. 7 9 7 Select the correct answer from above options...
asked Nov 15, 2021 in Education by JackTerrance
0 votes
0 votes
    If the probability of a random variable X is a given below : X=x: -2 -1 0 1 2 3 P(X=x): 1 2 k 1 5 2k 3 10 ... B. 2 10 C. 3 10 D. 7 10 Select the correct answer from above options...
asked Nov 16, 2021 in Education by JackTerrance
0 votes
0 votes
0 votes
    Two natural numbers x and y are chosen at random from the set {1,2,3,4,...3n}. find the probability that x2-y2 is ... D. 3n-1 2(5n-3) Select the correct answer from above options...
asked Nov 15, 2021 in Education by JackTerrance
0 votes
    Two numbers a and b are chosen at random from the set {1,2,3,..,3n}. The probability that a3+b3 is divisible by 3, ... ) C. 1 6 D. 1 3 Select the correct answer from above options...
asked Nov 15, 2021 in Education by JackTerrance
0 votes
    Two numbers a and b are chosen at random from the set {1,2,3,..,5n}. The probability that a4-b4 is divisible ... -1) D. none of these Select the correct answer from above options...
asked Nov 15, 2021 in Education by JackTerrance
0 votes
0 votes
0 votes
    A five digit number is formed but the digits 1,2,3,4,5 without repetition. Find the probability that the number is ... 1 5 D. 6 5 Select the correct answer from above options...
asked Nov 15, 2021 in Education by JackTerrance
0 votes
    A five digit number if formed by the digits 1,2,3,4,5,6 and 8. The probability that the number has even digit ... 2 7 D. none of these Select the correct answer from above options...
asked Nov 15, 2021 in Education by JackTerrance
...