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Recent questions and answers in Combinatory
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UGCNETDec2012III25
The number of distinct bracelets of five beads made up of red, blue and green beads (two bracelets are indistinguishable if the rotation of one yield another) is, 243 81 51 47
answered
May 15
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Combinatory
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Kuljeet Shan
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ugcnetdec2012iii
0
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1
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2
Recurrence Relation SelfDoubt
What will be solution of recurrence relation if roots are like this: r1=2, r2=2, r3=2, r4=2 is this the case of repetitive roots?
answered
May 14
in
Combinatory
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Raghava45
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321
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relations
recurrence
recurrenceeqation
discretemathematics
combinational
0
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2
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3
Recurrence Relation
Let $T(n) = T(n1) + \frac{1}{n} , T(1) = 1 ;$ then $T(n) = ? $ $O(n^{2})$ $O(logn)$ $O(nlogn)$ $O(n^{2}logn)$
answered
May 14
in
Combinatory
by
Raghava45
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321
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123
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discretemathematics
recurrence
relations
recurrenceeqation
0
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0
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4
Rosen 7e Exercise 8.2 Questionno26 page no525 Recurrence Relation
What is the general form of the particular solution guaranteed to exist of the linear nonhomogeneous recurrence relation $a_n$=$6a_{n1}$$12a_{n2}$+$8a_{n3}$+F(n) if F(n)=$n^2$ F(n)=$2^n$ F(n)=$n2^n$ F(n)=$(2)^n$ F(n)=$n^22^n$ F(n)=$n^3(2)^n$ F(n)=3
asked
May 14
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Combinatory
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aditi19
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27
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kennethrosen
discretemathematics
#recurrencerelations
recurrence
0
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0
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5
Rosen 7e Exercise8.2 Question no23 page no525 Recurrence Relation
Consider the nonhomogeneous linear recurrence relation $a_n$=$3a_{n1}$+$2^n$ in the book solution is given $a_n$=$2^{n+1}$ but I’m getting $a_n$=$3^{n+1}2^{n+1}$
asked
May 13
in
Combinatory
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aditi19
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3.5k
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18
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kennethrosen
discretemathematics
#recurrencerelations
recurrence
0
votes
1
answer
6
ISI2018MMA10
A new flag of ISI club is to be designed with $5$ vertical strips using some or all of the four colors: green, maroon, red and yellow. In how many ways this can be done so that no two adjacent strips have the same color? $120$ $324$ $424$ $576$
answered
May 13
in
Combinatory
by
Sayan Bose
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6.9k
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21
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isi2018
engineeringmathematics
discretemathematics
permutationsandcombinations
0
votes
2
answers
7
#probability(self doubt)
An automobile showroom has 10 cars, 2 of which are defective. If you are going to buy the 6th car sold that day at random, then the probability of selecting a defective car is??
answered
May 13
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Combinatory
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srestha
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114k
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30
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#probability
self
doubt
+1
vote
1
answer
8
ISI2018MMA26
Let $C_i(i=0,1,2...n)$ be the coefficient of $x^i$ in $(1+x)^n$.Then $\frac{C_0}{2} – \frac{C_1}{3}+\frac{C_2}{4}\dots +(1)^n \frac{C_n}{n+2}$ is equal to $\frac{1}{n+1}\\$ $\frac{1}{n+2}\\$ $\frac{1}{n(n+1)}\\$ $\frac{1}{(n+1)(n+2)}$
answered
May 11
in
Combinatory
by
srestha
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114k
points)

99
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isi2018
engineeringmathematics
discretemathematics
generatingfunctions
0
votes
2
answers
9
ISI2019MMA27
A general election is to be scheduled on $5$ days in May such that it is not scheduled on two consecutive days. In how many ways can the $5$ days be chosen to hold the election? $\begin{pmatrix} 26 \\ 5 \end{pmatrix}$ $\begin{pmatrix} 27 \\ 5 \end{pmatrix}$ $\begin{pmatrix} 30 \\ 5 \end{pmatrix}$ $\begin{pmatrix} 31 \\ 5 \end{pmatrix}$
answered
May 11
in
Combinatory
by
amolcharpe
(
27
points)

2.7k
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isi2019
engineeringmathematics
discretemathematics
permutationsandcombinations
0
votes
2
answers
10
ISI2019MMA20
Suppose that the number plate of a vehicle contains two vowels followed by four digits. However, to avoid confusion, the letter ‘O’ and the digit ‘0’ are not used in the same number plate. How many such number plates can be formed? $164025$ $190951$ $194976$ $219049$
answered
May 9
in
Combinatory
by
Utkarsh Joshi
Loyal
(
7.6k
points)

281
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isi2019
engineeringmathematics
discretemathematics
permutationsandcombinations
0
votes
0
answers
11
A first course in probability by Sheldon Ross
What are the relevant chapter of probability by sheldon ross to study for gate? I think whole syllabus is within chapter 5,Should i study everything upto chapter 5 or there are some topics that can be skipped.
asked
May 8
in
Combinatory
by
souren
(
21
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21
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probability
sheldonross
0
votes
1
answer
12
ISI2019MMA2
The number of $6$ digit positive integers whose sum of the digits is at least $52$ is $21$ $22$ $27$ $28$
answered
May 6
in
Combinatory
by
pratekag
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2k
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213
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isi2019
engineeringmathematics
discretemathematics
permutationsandcombinations
0
votes
1
answer
13
ISI2019MMA4
Suppose that $6$digit numbers are formed using each of the digits $1, 2, 3, 7, 8, 9$ exactly once. The number of such $6$digit numbers that are divisible by $6$ but not divisible by $9$ is equal to $120$ $180$ $240$ $360$
answered
May 6
in
Combinatory
by
pratekag
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(
2k
points)

173
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isi2019
engineeringmathematics
discretemathematics
permutationsandcombinations
0
votes
1
answer
14
UPPCL AE 2018:66
answered
May 3
in
Combinatory
by
Abhisek Tiwari 4
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4.7k
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25
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uppcl2018
0
votes
2
answers
15
Suppose a 6 digit number N is formed by rearranging the digits of the number 123456
answered
May 1
in
Combinatory
by
kratos
(
11
points)

522
views
permutationsandcombinations
0
votes
0
answers
16
Rosen 7e Recurrence Relation Exercise8.1 Question no25 page no511
How many bit sequences of length seven contain an even number of 0s? I'm trying to solve this using recurrence relation Is my approach correct? Let T(n) be the string having even number of 0s T(1)=1 {1} T(2)=2 {00, 11} T(3)=4 {001, ... add 0 to strings of length n1 having odd number of 0s T(n)=T(n1) Hence, we have T(n)=2T(n1)
asked
Apr 29
in
Combinatory
by
aditi19
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3.5k
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34
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kennethrosen
discretemathematics
permutationsandcombinations
#recurrencerelations
recurrence
0
votes
1
answer
17
Rosen 7e Exercise8.1 Question no10 Page no511
Find a recurrence relation for the number of bit strings of length n that contain the string 01.
answered
Apr 28
in
Combinatory
by
srestha
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(
114k
points)

34
views
kennethrosen
discretemathematics
combinatory
#recurrencerelations
recurrence
+1
vote
1
answer
18
Pgee 2013
You have a box containing 10 black and 10 blue socks.What is the minimum number of times you need to pull out so that you have a pair of the same color?
answered
Apr 22
in
Combinatory
by
Manas Mishra
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2.8k
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84
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iiithpgee
0
votes
0
answers
19
Kenneth H Rosen 7th edition
Please see example 6. l am not getting the mathematical insight. Can anyone please tell how they are arriving at the answer.
asked
Apr 21
in
Combinatory
by
Psnjit
(
211
points)

41
views
kennethrosen
discretemathematics
permutationsandcombinations
+2
votes
1
answer
20
Rosen 7e Exercise6.5 question 45.b page 433
How many ways can n books be placed on k distinguishable shelves if no two books are the same, and the positions of the books on the shelves matter?
answered
Apr 20
in
Combinatory
by
ma1999
(
11
points)

154
views
kennethrosen
discretemathematics
permutationsandcombinations
combinatory
0
votes
1
answer
21
Madeeasy Discrete Maths notes
How many 5 letter word possible having atleast 2 a's ?
answered
Apr 9
in
Combinatory
by
tusharp
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(
6.5k
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59
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madeeasynotes
discretemathematics
permutationsandcombinations
0
votes
1
answer
22
Self doubt
How is the problem.. Distribute 5 toys such that each of 3 child get atleast 1 Different from sum of 3 no. X+y+z=5 such that each digit >= 1. Plz explain ?
answered
Apr 4
in
Combinatory
by
hitendra singh
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1.8k
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56
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permutationsandcombinations
0
votes
0
answers
23
Combinatorics
There are 6n flowers of one type and 3 flowers of second type, total no. Of garlands possible?
asked
Apr 2
in
Combinatory
by
Manoj Kumar Pandey
(
179
points)

15
views
permutationsandcombinations
0
votes
0
answers
24
General Query: Self doubt(Math+Automata)
Can somebody explain What is identity permutation?
asked
Apr 1
in
Combinatory
by
srestha
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(
114k
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23
views
discretemathematics
finiteautomata
0
votes
0
answers
25
website
There is 4 coins 1 paisa, 5 paise, 10 paise, 25 paise using these coins we have to make 50 paisa how many combination can we make ?
asked
Mar 31
in
Combinatory
by
Cristine
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1.6k
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26
views
permutationsandcombinations
+1
vote
3
answers
26
MadeEasy Subject Test 2019: Combinatory  Permutations And Combinations
Q.The number of ways, we can arrange 5 books in 3 shelves ________.
answered
Mar 26
in
Combinatory
by
Arkaprava
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(
1.1k
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360
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discretemathematics
permutationsandcombinations
madeeasytestseries2019
madeeasytestseries
+3
votes
2
answers
27
GATE20195
Let $U = \{1, 2, \dots , n\}$ Let $A=\{(x, X) \mid x \in X, X \subseteq U \}$. Consider the following two statements on $\mid A \mid$. $\mid A \mid = n2^{n1}$ $\mid A \mid = \Sigma_{k=1}^n k \begin{pmatrix} n \\ k \end{pmatrix}$ Which of the above statements is/are TRUE? Only I Only II Both I and II Neither I nor II
answered
Mar 25
in
Combinatory
by
KINGSLAYER
(
75
points)

2.3k
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gate2019
engineeringmathematics
discretemathematics
permutationsandcombinations
0
votes
0
answers
28
Allen Career Institute: Discrete Mathematics
A certain software was being tested by using error seeding strategy in which $22$ errors were seeded. $14$ of seeded errors were detected apart from $140$ unseeded errors when the code was tested using the complete test suit. Calculate the estimated no. of undetected errors in the code after complete testing _____
asked
Mar 22
in
Combinatory
by
srestha
Veteran
(
114k
points)

29
views
discretemathematics
permutationsandcombinations
0
votes
1
answer
29
MadeEasy Full Length Test 2019: Combinatory  Permutations And Combinations
The number of ways 5 letter be put in 3 letter boxes A,B,C. If letter box A must contain at least 2 letters.
answered
Mar 19
in
Combinatory
by
vizzard110
(
11
points)

159
views
discretemathematics
permutationsandcombinations
madeeasytestseries2019
madeeasytestseries
+1
vote
1
answer
30
Model Question IISc CDS CS Written Test Sample question
Anand is preparing a pizza with 8 slices, and he has 10 toppings to put on the pizza. He can put only one topping on each slice but can use the same topping on zero or more slices. In how many unique ways can he prepare the slices so that the same topping is not used in adjacent slices?
answered
Mar 15
in
Combinatory
by
Arkaprava
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1.1k
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177
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iisc
cds
+10
votes
5
answers
31
TIFR2015A7
A $1 \times 1$ chessboard has one square, a $2 \times 2$ chessboard has five squares. Continuing along this fashion, what is the number of squares on the regular $8 \times 8$ chessboard? $64$ $65$ $204$ $144$ $256$
answered
Mar 15
in
Combinatory
by
Debargha Bhattacharj
(
225
points)

630
views
tifr2015
permutationsandcombinations
+13
votes
5
answers
32
GATE200334
$m$ identical balls are to be placed in $n$ distinct bags. You are given that $m \geq kn$, where $k$ is a natural number $\geq 1$. In how many ways can the balls be placed in the bags if each bag must contain at least $k$ ... $\left( \begin{array}{c} m  kn + n + k  2 \\ n  k \end{array} \right)$
answered
Mar 9
in
Combinatory
by
Debargha Bhattacharj
(
225
points)

2k
views
gate2003
permutationsandcombinations
ballsinbins
normal
+17
votes
3
answers
33
GATE200213
In how many ways can a given positive integer $n \geq 2$ be expressed as the sum of $2$ positive integers (which are not necessarily distinct). For example, for $n=3$ the number of ways is $2$, i.e., $1+2, 2+1$. Give only the answer ... integer $n \geq k$ be expressed as the sum of $k$ positive integers (which are not necessarily distinct). Give only the answer without explanation.
answered
Mar 9
in
Combinatory
by
Debargha Bhattacharj
(
225
points)

1k
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gate2002
permutationsandcombinations
normal
descriptive
+2
votes
1
answer
34
Rosen 7e, Advance Counting techniques , Question 6.f
Find the generating function for the sequence $\left \{ a_n \right \} where $ $a_n = \Large \binom{10}{n+1} $ ... $\Large \color{red}{ \frac{( 1+x )^{10}  1}{x} }$ Please verify
answered
Mar 9
in
Combinatory
by
Debdeep1998
Junior
(
635
points)

41
views
kennethrosen
discretemathematics
generatingfunctions
0
votes
1
answer
35
ACE Test Series: Generating Function
The generating function of the sequence $\left \{ a_{0},a_{1},a_{2}..........a_{n}………...\infty \right \}$ where $a_{n}=\left ( n+2 \right )\left ( n+1 \right ).3^{n}$ is $a)3\left ( 1+3x \right )^{2}$ $b)3\left ( 13x \right )^{2}$ $c)2\left ( 1+3x \right )^{3}$ $d)2\left ( 13x \right )^{3}$
answered
Mar 9
in
Combinatory
by
ankitgupta.1729
Boss
(
11.3k
points)

59
views
generatingfunctions
discretemathematics
0
votes
1
answer
36
Kenneth Rosen Edition 6th Exercise 6.1 Example 7 (Page No. 399)
this is an example taken from Rosen. but I’m unable to understand to understand the solution given there can someone pls explain me in details
answered
Mar 4
in
Combinatory
by
Gawade Sahadev
(
291
points)

54
views
kennethrosen
discretemathematics
#recurrencerelations
counting
+8
votes
7
answers
37
Kenneth Rosen Edition 6 Question 45 (Page No. 346)
How many bit strings of length eight contain either three consecutive 0s or four consecutive 1s?
answered
Mar 3
in
Combinatory
by
srestha
Veteran
(
114k
points)

2k
views
permutationsandcombinations
counting
0
votes
1
answer
38
Rosen Ex.6.1
Find a recurrence relation for the number of ways to lay out a walkway with slate tiles if the tiles are red, green, or gray so that no two red tiles are adjacent and tiles of the same color are considered indistinguishable
answered
Mar 3
in
Combinatory
by
vipul2097
(
165
points)

31
views
0
votes
1
answer
39
#Combinatorics
answered
Mar 1
in
Combinatory
by
Satbir
Loyal
(
7.5k
points)

101
views
0
votes
0
answers
40
Pg 345 Question 23, 6th Edition KH Rosen
How many strings of three decimal digits do not contain the same digit three times? have exactly two digits that are 4s? I know question is easy but the answer is not matching with the one given over here Please someone verify.. Does the word “string” mean that we can take 0 as the first digit as well?
[closed]
asked
Feb 27
in
Combinatory
by
MiNiPanda
Boss
(
22k
points)

45
views
kennethrosen
discretemathematics
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