Ask Questions, Get Answers
Menu
X
JEEMAIN Crash Practice
15 Test Series
NEET Crash Practice
15 Test Series
CBSE XII
Math
JEEMAIN
Math
Physics
Chemistry
Practice Test Series
CBSE XI
Math
NEET
Physics
Chemistry
Biology - XII
Biology - XI
Olympiad class V
Math - 5 Test Series
Olympiad class VI
Math - 5 Test Series
CBSE XII Board Exam Series
BES Math
BES Physics
BES Chemistry
BES Biology
studyplans
JEEMAIN Crash Practice
15 Test Series
NEET Crash Practice
15 Test Series
CBSE XII
Math
JEEMAIN
Math
Physics
Chemistry
Practice Test Series
CBSE XI
Math
NEET
Physics
Chemistry
Biology - XII
Biology - XI
Olympiad class V
Math - 5 Test Series
Olympiad class VI
Math - 5 Test Series
CBSE XII Board Exam Series
BES Math
BES Physics
BES Chemistry
BES Biology
mobile
exams
ask
sample papers
tutors
pricing
login
X
ASK
Home
>>
CBSE XI
>>
Math
>>
Permutations and Combinations
Find the number of permutations of n distinct things taken r together in which 3 particular things must occur together.
$\begin{array}{1 1}(A)\;n-3C_{r-3}(r-2)!3!\\(B)\;nC_r\\(C)\;n-1C_{r-1}\\(D)\;n-2C_{r-3}\end{array} $
cbse
math
class11
ch7
permutations-and-combinations
exercise7-3
exemplar
q9
sec-b
medium
Share
asked
May 15, 2014
by
sreemathi.v
Please
log in
or
register
to add a comment.
Please
log in
or
register
to answer this question.
1 Answer
The number of permutations of n distinct things taken r together =$nC_r$
3 things together =$(n-3)C_{r-3}$
$\Rightarrow (n-3)C_{r-3}(r-2)!3!$
Hence (A) is the correct answer.
answered
May 15, 2014
by
sreemathi.v
Please
log in
or
register
to add a comment.
Related questions
True-or-False:In the permutations of n things,r taken together,the number of permutation in which m particular things occur together is $(n-m)P_{r-m}\times rP_m$
cbse
math
class11
ch7
permutations-and-combinations
exercise7-3
true-or-false
exemplar
q53
sec-a
easy
asked
May 16, 2014
by
sreemathi.v
1
answer
The number of permutations of n different objects,taken r at a line,when repetitions are allowed is
cbse
math
class11
ch7
permutations-and-combinations
exercise7-3
exemplar
q43
sec-a
easy
asked
May 16, 2014
by
sreemathi.v
1
answer
In how many of the distinct permutations of the letters in MISSISSIPPI do the four $'I'$s not come together?
cbse
math
class11
bookproblem
ch7
permutations-and-combinations
exercise7-3
q10
sec-b
medium
asked
May 13, 2014
by
sreemathi.v
1
answer
The total number of ways in which six '+' and four '-' signs can be arranged in a line such that no two signs '-' occur together is
cbse
math
class11
ch7
permutations-and-combinations
exercise7-3
exemplar
q48
sec-b
medium
asked
May 16, 2014
by
sreemathi.v
1
answer
There are 10 persons named $P_1,P_2,P_3.....P_{10}$.Out of 10 persons,5 person are to be arranged in a line such that in each arrangement $P_1$ must occur where as $P_4$ and $P_5$ do not occur.Find the number of such possible arrangement.
cbse
math
class11
ch7
permutations-and-combinations
exercise7-3
exemplar
q12
sec-b
medium
asked
May 15, 2014
by
sreemathi.v
1
answer
In how many ways can the letters of the word PERMUTATIONS be arranged if the Vowels are together?
cbse
math
class11
bookproblem
ch7
permutations-and-combinations
exercise7-3
q11-ii
sec-b
medium
asked
May 13, 2014
by
sreemathi.v
1
answer
A bag contains six white marbles and five red marbles.Find the number of ways in which four marbles can be drawn from the bag if they must all be of the same colour
cbse
math
class11
ch7
permutations-and-combinations
exercise7-3
exemplar
q22-c
sec-b
medium
asked
May 15, 2014
by
sreemathi.v
1
answer
Ask Question
Tag:
Math
Phy
Chem
Bio
Other
SUBMIT QUESTION
►
Please Wait
Take Test
JEEMAIN Crash Practice
15 Test Series
NEET Crash Practice
15 Test Series
JEEMAIN
350+ TESTS
NEET
320+ TESTS
CBSE XI MATH
50+ TESTS
CBSE XII MATH
80+ TESTS
...