Advertisements
Advertisements
Question
Evaluate `("n"!)/("r"!("n" - "r")!)` when n = 5 and r = 2.
Advertisements
Solution
`("n"!)/("r"!("n" - "r")!) = (5!)/(2!(5 - 2)!) = (5!)/(2! xx 3!) = (5 xx 4 xx 3 xx 2 xx 1)/(2 xx 1 xx 3 xx 2 xx 1)` = 10
APPEARS IN
RELATED QUESTIONS
Is 3! + 4! = 7!?
Find r if `""^5P_r = 2^6 P_(r-1)`
In how many of the distinct permutations of the letters in MISSISSIPPI do the four I’s not come together?
Three dice are rolled. Find the number of possible outcomes in which at least one die shows 5 ?
In how many ways can 7 letters be posted in 4 letter boxes?
Write the number of arrangements of the letters of the word BANANA in which two N's come together.
Find x if `1/(6!) + 1/(7!) = x/(8!)`
8 women and 6 men are standing in a line. In how many arrangements will no two men be standing next to one another?
Find the sum of all 4-digit numbers that can be formed using digits 1, 2, 3, 4, and 5 repetitions not allowed?
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)`
