Permutations & Combinations Questions (855)

Group A has 7 boys and 3 girls; Group B has 6 boys and 5 girls. A team of 4 boys and 4 girls is to be selected such that exactly 5 members come from Group A and 3 from Group B. The number of ways is
The number of words formed from all the letters of DAUGHTER such that all vowels are never together is
The number of triangles whose vertices are at the vertices of a regular octagon but none of whose sides is a side of the octagon is
Find the sum of all the odd numbers of five digits that can be made with the digits 0, 1, 4, 5, 4.
In an examination a candidate has to pass in each of the papers. If the total number of different ways in which the candidate can fail is 63 then find the number of papers in the examination.
If the number of 6 digit natural numbers such that sum of their digits is 10 and digits 0, 1, 2 and 3 occur at least once in them is k then find k/100
From a group of 7 batsmen and 6 bowlers, 10 players are to be chosen for a team, which should include atleast 4 batsmen and atleast 4 bowlers. One batsmen and one bowler who are captain and$vice-captain$respectively of the team should be included. Then the total number of ways such a selection can be made, is
Let p be the number of all triangles that can be formed by joining the vertices of a regular polygon P of n sides and q be the number of all quadrilaterals that can be formed by joining the vertices of P. If$p + q = 126$, then the 2 2 y eccentricity of the ellipse is: x + = 1 16 n
Line L of slope 2 and line L of slope 1 2 1 2 intersect at the origin O. In the first quadrant, P, P,$\ldots. P 1 2 12 are 12 points o_n line L and Q, Q,$$\ldots.. Q are 9 points o_n line L. Then the total number of triangles, that can be 1 1 2 9 2 formed having vertices at three of the 22 points O, P, P,$$\ldots P, Q, Q,$$\ldots. Q, is$: 1 2 12 1 2 9
Find the value of r, if \(^8P_5 + 5 \cdot \,^8P_4 = \,^9P_r\)
For a game in which every possible pair plays with every other pair, 10 players are available. Mr. A solves this problem and get an answer equal to \(\frac{10 !^{5} C_{2}}{(2 !)^{5} 5 !}\). However on checking the answer, he found that his answer is k times the actual answer, then the value of k is:
Number of 5-digit natural numbers such that product of their digits equals number of ways to create a necklace out of 6 beads from 10 distinct beads is
Number of natural numbers with 5 distinct digits formed using $\{1,2,3,5,6,7,9\}$ and divisible by 6 are
Find the number of ways in which five different letters can be put in their five addressed envelopes so that all the letters are in the wrong envelopes.
Let $A=\{1,2,3,\ldots,10\}$, $B=\{4,8,12,16,20\}$ and $C=\{D:D\subseteq A,\,D\cap B\neq\emptyset\}$. The number of elements in $C$ which have at least 3 but at most 6 cardinal number is
The sum of the odd divisors of $10!$ is
There are tea cups with and without handles. The number of ways of selecting 2 without handle and 3 with handle is exactly 1200. What is the maximum possible number of cups in the kitchen?
If $\binom{40}{0}+\binom{41}{1}+\binom{42}{2}+\cdots+\binom{60}{20}=\dfrac{m}{n}\binom{60}{20}$, $\gcd(m,n)=1$, max value of $m+n$ is
Four-digit numbers are formed using digits from $\{0,1,2,3,4,5\}$, repetition allowed. Statement $S_1$: the number of such odd numbers is 480. Statement $S_2$: the number formed with exactly three different digits is 360.
Let $A=\sum_{i=0}^{2023}\sum_{j=0}^{2023}\min\{\binom{2023}{i},\binom{2023}{j}\}$ and $B=\sum_{i=0}^{2023}\sum_{j=0}^{2023}\max\{\binom{2023}{i},\binom{2023}{j}\}$. Then $A+B$ equals
If $p$, $q$, $r$ are prime numbers and $\alpha$, $\beta$, $\gamma$ are positive integers such that $\mathrm{lcm}(\alpha,\beta,\gamma)=p^3q^2r$ and $\gcd(\alpha,\beta,\gamma)=pqr$, then the number of possible ordered triplets $(\alpha,\beta,\gamma)$ is:
If $p$, $q$, $r$ are prime numbers and $\alpha$, $\beta$, $\gamma$ are positive integers such that $\mathrm{lcm}(\alpha,\beta,\gamma)=p^3q^2r$ and $\gcd(\alpha,\beta,\gamma)=pqr$, then the number of possible ordered triplets $(\alpha,\beta,\gamma)$ is:
Sudheer has 7 friends. He writes 7 letters, each uniquely meant for one friend, and places them randomly into 7 addressed envelopes, each bearing the specific name of the intended friend. Out of the seven friends: 1) Two of them are brothers and live at the same address. 2) The other five friends live at five different addresses. Find the number of ways Sudheer can place the letters into the addressed envelopes such that none of the friends receives the letter meant for them. (Assume that letters received at the two brothers' address are received by both.)
The total number of positive integral solutions of $15 < x_1+x_2+x_3 \leq 20$ is equal to:
Ten women sit in 10 seats in a line. All 10 get up and then reseat themselves using all 10 seats, each sitting in the seat she was in before or a seat next to the one she occupied before. The number of ways the women can be reseated is:
The total number of positive integral solutions of $15 < x_1+x_2+x_3 \leq 20$ is equal to:
Let $A=\{1,2,\ldots,26\}$. Match each type of relation on $A$ with the count formula and find $p+q$, $p+q+r$, etc. **List-I:** P) Asymmetric relations=$p^q$ ($p$ prime), find $p+q$; Q) Reflexive but not symmetric $=p^q(p^q-p^r)$, find $p+q+r$; R) Symmetric but not reflexive (non-empty) $=p^q(p^r-1)-1$, find $p+q+r$; S) Neither symmetric nor reflexive (non-empty) $=(p^s-1)p^q(p^q-1)$, find $p+q+s$ **List-II:** 1)328; 2)329; 3)330; 4)353; 5)356
Sudheer has 7 friends. He writes 7 letters, each uniquely meant for one friend, and places them randomly into 7 addressed envelopes, each bearing the specific name of the intended friend. Out of the seven friends: 1) Two of them are brothers and live at the same address. 2) The other five friends live at five different addresses. Find the number of ways Sudheer can place the letters into the addressed envelopes such that none of the friends receives the letter meant for them. (Assume that letters received at the two brothers' address are received by both.)
Let $A=\{1,2,\ldots,26\}$. Match each type of relation on $A$ with the count formula and find $p+q$, $p+q+r$, etc. **List-I:** P) Asymmetric relations=$p^q$ ($p$ prime), find $p+q$; Q) Reflexive but not symmetric $=p^q(p^q-p^r)$, find $p+q+r$; R) Symmetric but not reflexive (non-empty) $=p^q(p^r-1)-1$, find $p+q+r$; S) Neither symmetric nor reflexive (non-empty) $=(p^s-1)p^q(p^q-1)$, find $p+q+s$ **List-II:** 1)328; 2)329; 3)330; 4)353; 5)356
Ten women sit in 10 seats in a line. All 10 get up and then reseat themselves using all 10 seats, each sitting in the seat she was in before or a seat next to the one she occupied before. The number of ways the women can be reseated is:
Triplet \((x, y, z)\) is chosen from the set \(\{1,2,3, \ldots, n\}\), such that \(x \leq y \lt z\). The number of such triplets is
\({ }^{n-1} {C}_{r}=\left(k^{2}-8\right)^{n} {C}_{r+1}\) if and only if:
The number of ways in which the letters of the word PERSON can be placed in the squares of the given figure so that no row remains empty is
Six Xs are to be placed in the squares of the given figure, such that each row contains at least one X. In how many different ways can this be done?
5 boys and 4 girls stand in a row. The number of ways such that all 5 boys stand together OR no two boys stand adjacent to each other is
There are 10 seats in a double decker bus, 6 in the lower deck and 4 on the upper deck. Ten passenger board the bus, of them 3 refuse to go to the upper deck and 2 insist on going up. The number of way in which the passengers can be accommodated is: (Assume all seats to be duly numbered)
An ice cream parlour has ice creams in eight different varieties. Number of ways of choosing $3$ ice creams taking atleast two are of the same variety, is: (Assume that ice creams of the same variety to be identical & available in unlimited supply)
The largest $n\in\mathbb{N}$, for which $7^n$ divides $101!$, is:
An old man while dialing a 7 digit telephone number remembers that the first four digits consists of one 1's, one 2's and two 3's. He also remembers that the fifth digit is either a 4 or 5 while has no memory of the sixth digit, he remembers that the seventh digit is 9 minus the sixth digit. Maximum number of distinct trials he has to try to make sure that he dials the correct telephone number, is
5-digit numbers $>40000$, divisible by 5, from $\{0,1,3,5,7,9\}$ without repetition is equal to
The letters of the word OUGHT are written in all possible ways and these words are arranged as in a dictionary, in a series. Then the serial number of the word TOUGH is:
Number of positive integral solutions satisfying the equation $(x_1 + x_2 + x_3)(y_1 + y_2) = 77$, is:
If words from MATHEMATICS with C and S not together $=(6!)k$, then $k$ is equal to
Let $S$ denote the set of 4-digit numbers $abcd$ such that $a>b>c>d$ and $P$ denote the set of 5-digit numbers having product of its digits equal to 20. Then $n(S)+n(P)$ is equal to _____.
The number of ways in which 8 distinguishable apples can be distributed among 3 boys such that every boy should get atleast 1 apple and atmost 4 apples is $K \cdot P_r$ where K has the value equal to:
If all the six digit numbers x₁x₂x₃x₄x₅x₆ with 0 < x₁ < x₂ < x₃ < x₄ < x₅ < x₆ are arranged in the increasing order, then the sum of the digits in the 72nd number is _____.
The number of ways of selecting two numbers a and b, \(a \in \{2, 4, 6, \ldots, 100\}\) and \(b \in \{1, 3, 5, \ldots, 99\}\) such that 2 is the remainder when a + b is divided by 23 is
The number of 4-letter words, with or without meaning, which can be formed using the letters PQRPQRSTUVP, is _____.
It $5$ letters are put in the $5$ envelopes. Find the no. of ways so that atleast $2$ letters are in wrong envelope:
The largest value of $n$, for which $40^n$ divides $60!$, is