Ask Questions, Get Answers
Menu
X
JEEMAIN Crash Practice
15 Test Series
NEET Crash Practice
5 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
studyplans
JEEMAIN Crash Practice
15 Test Series
NEET Crash Practice
5 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
mobile
exams
ask
sample papers
teach
pricing
sign-in
Download our FREE mobile app with 1000+ tests for CBSE, JEE MAIN, NEET
X
Search
Topics
Want to ask us a question?
Click here
Browse Questions
Student Questions
Ad
Home
>>
JEEMAIN and AIPMT
>>
Mathematics
>>
Class11
>>
Permutations and Combinations
0
votes
How many 7 digit numbers are there using the digits,1,2,3 and '2' should occur 2 times in each of the number?
jeemain
math
class11
ch7
permutations-and-combinations
combinations
medium
Share
asked
Sep 3, 2013
by
rvidyagovindarajan_1
edited
Aug 5, 2014
by
sharmaaparna1
Please
log in
or
register
to add a comment.
Can you answer this question?
Do not ask me again to answer questions
Please
log in
or
register
to answer this question.
1 Answer
0
votes
Since 2 occur twice, to fix 2 $2^s$, we have to choose
any two places out of 7 (7digit numbers)
This can be done in $^7C_2$ ways.
Remaining 5 places can be fixed by any of the two numbers, 1or 2
This can be done in $2^5$ ways.
$\therefore$ The required number of 7 digit numbers = $2^5.^7C_2$
answered
Sep 3, 2013
by
rvidyagovindarajan_1
Please
log in
or
register
to add a comment.
Related questions
0
votes
1
answer
How many 6 digit numbers can be formed using the digits $1,2,3$ so that the digit 1 occur 2 times in each number?
asked
Aug 15, 2013
by
rvidyagovindarajan_1
jeemain
math
class11
ch7
permutations-and-combinations
combinations
difficult
0
votes
1
answer
How many numbers are there between 20000 and 30000 in which the digits are 2,3,5,6,7 and each digit can be repeated any number of times.
asked
Aug 20, 2013
by
rvidyagovindarajan_1
jeemain
math
class11
ch7
permutations-and-combinations
fundamental-principle-of-counting
easy
0
votes
1
answer
How many 6 digit numbers can be formed using the digits 1,2,3,4 so that each of the digits should come atleast once in each number?
asked
Sep 4, 2013
by
rvidyagovindarajan_1
jeemain
math
class11
ch7
permutations-and-combinations
medium
0
votes
1
answer
The total number of 4 digit numbers in which the digits are in descending order is ?
asked
Sep 3, 2013
by
rvidyagovindarajan_1
jeemain
math
class11
ch7
permutations-and-combinations
combinations
medium
0
votes
1
answer
How many 6 digit numbers can be formed using the digits 0,1,3,5,7,9 that are divisible by 5? (digits should not be repeated)
asked
Aug 31, 2013
by
rvidyagovindarajan_1
jeemain
math
class11
ch7
permutations-and-combinations
fundamental-principle-of-counting
easy
0
votes
1
answer
There are 12 points in a plane out of which 7 points lie on a st. line (collinear). How many triangles can be formed using these points as vertices?
asked
Aug 12, 2013
by
rvidyagovindarajan_1
jeemain
math
class11
ch7
permutations-and-combinations
combinations
easy
0
votes
1
answer
How many number of times the digit '5' appear in listing the integers from 1 to 1000?
asked
Aug 15, 2013
by
rvidyagovindarajan_1
jeemain
math
class11
ch7
permutations-and-combinations
combinations
difficult
Ask Question
SUBMIT QUESTION
►
Please Wait
Take Test
JEEMAIN Crash Practice
15 Test Series
NEET Crash Practice
5 Test Series
JEEMAIN
350+ TESTS
NEET
320+ TESTS
CBSE XI MATH
50+ TESTS
CBSE XII MATH
80+ TESTS
x
JEE MAIN, CBSE, NEET Mobile and Tablet App
The ultimate mobile app to help you crack your examinations
Get the Android App
...