Advertisements
Advertisements
Question
If nP4 = 12(nP2), find n.
Advertisements
Solution
Given that nP4 = 12(nP2)
n(n – 1) (n – 2) (n – 3) = 12n(n – 1)
Cancelling n(n – 1) on both sides we get
(n – 2) (n – 3) = 4 × 3
We have product of consecutive number on both sides with decreasing order.
n – 2 = 4
∴ n = 6
APPEARS IN
RELATED QUESTIONS
if `1/(6!) + 1/(7!) = x/(8!)`, find x
Find n if n – 1P3 : nP4 = 1 : 9
Find x in each of the following:
In how many ways can three jobs I, II and III be assigned to three persons A, B and C if one person is assigned only one job and all are capable of doing each job?
Evaluate each of the following:
The number of arrangements of the word "DELHI" in which E precedes I is
Find the number of arrangements that can be made out of the letters of the word “ASSASSINATION”.
If all permutations of the letters of the word AGAIN are arranged in the order as in a dictionary. What is the 49th word?
In how many ways 3 mathematics books, 4 history books, 3 chemistry books and 2 biology books can be arranged on a shelf so that all books of the same subjects are together.
Suppose m men and n women are to be seated in a row so that no two women sit together. If m > n, show that the number of ways in which they can be seated is `(m!(m + 1)!)/((m - n + 1)1)`
