Permutations & Combinations Questions (855)

The number of 6-letter words that can be formed using the letters of the word MATHS (M, A, T, H, S — all distinct), where every letter that appears in the word must appear at least twice, is
In how many ways can 17 persons depart from railway station in 2 cars and 3 autos, given that 2 particular persons depart by the same car (4 persons can sit in a car and 3 persons can sit in an auto)?
Find the number of odd proper divisors of \(3^p \times 6^m \times 21^n\).
Eight chairs are numbered 1 to 8. Two women and 3 men wish to occupy one chair each. First the women choose the chairs from amongst the chairs 1 to 4 and then men select from the remaining chairs. Find the total number of possible arrangements.
If \({}^nC_r = 84\), \({}^nC_{r-1} = 36\), and \({}^nC_{r+1} = 126\), then find the value of n.
The number of ways \(= {}^{21}C_0 + {}^{21}C_1 + {}^{21}C_2 + \cdots + {}^{21}C_{10}\)\(= \dfrac{2^{22}}{2}\)What is this equal to?
We know that \(A \times B\) will have eight elements. Out of these 8 elements, the total number of subsets containing 3 or more elements is \({}^8C_3 + {}^8C_4 + {}^8C_5 + {}^8C_6 + {}^8C_7 + {}^8C_8 = 2^8 - {}^8C_0 - {}^8C_1 - {}^8C_2\). The total number of subsets containing 3 or more elements is:
Statement-1: The number of ways of distributing 10 identical balls in 4 distinct boxes such that no box is empty is \({}^9C_3\).Statement-2: The number of ways of choosing any 3 places from 9 different places is \({}^9C_3\).
In how many ways can 3 ladies and 3 gentlemen be seated around a round table so that any two and only two of the ladies sit together?
There are 10 points in a plane of which no three points are collinear and four points are concyclic. The number of different circles that can be drawn through at least three points of these points is
How many numbers greater than a million can be formed with the digits 2, 3, 0, 3, 4, 2, 3?
The number of integral solutions of \(x + y + z = 0\) with \(x \geq -5\), \(y \geq -5\), \(z \geq -5\) is
Find number of positive integral solutions of the equation \(x + y + z = 12\).
Let 52 cards of a deck be arranged in a line. Number of ways in which cards appear in non-decreasing order of denomination is
The number of possible outcomes in a throw of \(n\) ordinary dice in which at least one of the dice shows an odd number is
Find the number of six-digit numbers that can be formed using the digits 0, 1, 2, 5, 7, 9 such that the number is divisible by 11.
Number of quadrilaterals that can be made using the vertices of the polygon of sides 'n' if exactly two adjacent sides of the quadrilateral are common to the sides of the n-gon, is
If the letters of the word SACHIN are arranged in all possible ways and these words are written out as in a dictionary, then the word SACHIN appears at series number
From 5 married couples (5 husbands and 5 wives), 2 husbands are selected for two different sides A and B of a game. Then their wives are excluded. From the remaining 3 wives, 2 wives are chosen, and they can interchange their sides. Find the total number of ways to form the two teams.
The number of ways in which 7 identical rings can be put on 5 fingers of a hand is ______, if each finger has at least one ring.
Find the value of r, if \(^{11}P_r = 990\)
Find the number of odd proper divisors of the number 35700. Also, find the sum of the odd proper divisors.
If all the words (with or without meaning) having five letters, formed using the letters of the word SMALL and arranged as in a dictionary, then the position of the word SMALL is
Find the number of rectangles excluding squares from a rectangle of size 9 × 6.
The number of times the digit 3 will be written when listing the integers from 1 to 1000, is
If n points are the vertices of a polygon, then find the total number of diagonals.
The total number of ways in which \(2n\) persons can be divided into \(n\) couples, is
There are 10 points in a plane, out of these 6 are collinear. If N is the number of triangles formed by joining these points, then find N.
In how many ways can the letters of the word DIPESH be placed in the squares of the adjoining figure so that no row remains empty?
If \(^{2n+1}P_{n-1} : ^{2n-1}P_n = 3 : 5\), then the value of \(n\) is equal to
If x y and x, y ∈ {1, 2, 3, ..., 10}, then find the number of ordered pairs (x, y).
In how many ways can 3 girls and 9 boys be seated in two vans, each having numbered seats, 3 in the front and 4 at the back? How many sitting arrangements are possible if 3 girls should sit together in the back row on adjacent seats?
Find the rank of the word MOTHER when all permutations of the letters M, O, T, H, E, R are arranged in alphabetical order.
How many different signals can be given using any number of flags from 4 flags of different colours?
Consider all functions \(f : \{1, 2, 3, 4\} \to \{1, 2, 3, 4\}\) which are one-one, onto and satisfy the following property: if \(f(k)\) is odd then \(f(k+1)\) is even, \(k = 1, 2, 3\). The number of such functions is:
An urn contains 5 red marbles, 4 black marbles and 3 white marbles. Find the number of ways in which 4 marbles can be drawn so that at most three of them are red.
Three persons enter a lift at the ground floor. The lift will go up to the 10th floor. The number of ways in which the three persons can exit the lift at three different floors, if the lift does not stop at the first, second and third floors, is equal to _____.
Let $ABC$ be a triangle. Consider four points $p_1,p_2,p_3,p_4$ on side $AB$, five points $p_5,p_6,p_7,p_8,p_9$ on side $BC$, and four points $p_{10},p_{11},p_{12},p_{13}$ on side $AC$. None of these points is a vertex of the triangle. Then the total number of pentagons that can be formed by taking all the vertices from the points $p_1,p_2,\ldots,p_{13}$ is _____.
For three digit numbers formed using digits from a set of 5 digits (where 0 is not included), and four digit numbers similarly formed, find the total count of required numbers.
Since at least one ball is in each box, for no box empty the formula is \({}^{(n-1)}C_{(r-1)} = {}^{(10-1)}C_{(4-1)} = {}^9C_3\), where \(n\) is the number of identical balls and \(r\) is the number of distinct boxes. The number of ways of choosing any 3 places from 9 different places is \({}^9C_3\). The number of ways of distributing 10 identical balls into 4 distinct boxes such that each box has at least one ball is:
Let $S=\{(m,n):m,n\in\{1,2,3,\ldots,50\}\}$. If the number of elements $(m,n)$ in $S$ such that $6^m+9^n$ is a multiple of 5 is $p$ and the number of elements $(m,n)$ in $S$ such that $m+n$ is a square of a prime number is $q$, then $p+q$ is equal to _____.
The number of numbers greater than 5000, less than 9000 and divisible by 3, that can be formed using the digits $0,1,2,5,9$, if the repetition of the digits is allowed, is _____.
Select the number of ways to choose 6 books taking not more than 2 of each subject.
Find the number of different words that can be formed using all the letters of the word DEEPMALA if two vowels are together and the other two are also together but separated from the first two.
Let x be the elements of the set A = \{1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 20, 24, 30, 40, 60, 120\} and x_1, x_2, x_3 be positive integers and d be the number of integral solutions of x_1 x_2 x_3 = x, then d is
Let $A = \{1, a_1, a_2, \ldots, a_{18}, 77\}$ be a set of integers with $1 < a_1 < a_2 < \ldots < a_{18} < 77$. Let $A+A = \{x+y : y\in A\}$ contain exactly 39 elements. Then $a_1+a_2+\ldots+a_{18}$ equals
Each of 5 women who attend a banquet checks her coat and hat with the receptionist on arrival. Upon leaving, each woman is given a coat and a hat at random. Find the number of ways these coats and hats may be distributed such that nobody gets back either her coat or her hat.
Five different digits from the set of numbers \(\{1, 2, 3, 4, 5, 6, 7\}\) are written in random order. How many numbers can be formed using 5 different digits from this set if the number is divisible by 9?
Let N be the number of integral solution of the equation \(x + y + z + w = 15\) where \(x \geq 0\), \(y > 5\), \(z \geq 2\) and \(w \geq 1\). Find the unit digit of N.
How many different words can be formed by jumbling the letters in the word MISSISSIPPI in which no two S are adjacent?