Ask a Doubt
Request a call back

Join NOW to get access to exclusive study material for best results

CBSE Class 11-science Answered

how do i know when to use permutation or combination
Asked by Saksham | 14 Sep, 2015, 10:26: PM
answered-by-expert Expert Answer
P e r m u t a t i o n colon W h e n space s e l e c t i o n space a n d space a r r a n g e m e n t space o f space t h i n g s space i n space a space d e f i n i t e space o r d e r space a r e space c o n s i d e r e d comma space t h e n space P e r m u t a t i o n space i s space u s e d. E x a m p l e colon I n space h o w space m a n y space w a y s space 7 space w i n d o w s space c a n space b e space p a i n t e d space f r o m space 4 space d i f f e r e n t space c o l o u r s space o f space p a i n t ? S o l u t i o n colon T h e space n u m b e r space o f space w a y s space i n space w h i c h space 7 space w i n d o w s space c a n space b e space p a i n t e d space f r o m space 4 space c o l o u r s space o f space p a i n t space i s space s a m e a s space t h e space n u m b e r space o f space a r r a n g e m e n t space o f space 7 space t h i n g s comma space t a k i n g space 4 space a t space a space t i m e. H e n c e space t h e space r e q u i r e d space n u m b e r equals P presuperscript 7 subscript 4 equals fraction numerator 7 factorial over denominator open parentheses 7 minus 4 close parentheses factorial end fraction equals 210 C o m b i n a t i o n colon W h e n space s e l e c t i o n s space a r e space m a d e space b y space t a k i n g space s o m e space o r space a l l space o f space t h e space t h i n g s comma space i r r e s p e c t i v e space o f space t h e i r space a r r a n g e m e n t s t h e n space C o m b i n a t i o n space i s space u s e d. E x a m p l e colon I f space t h e r e space a r e space 25 space p e r s o n s space i n space a space p a r t y comma space a n d space e a c h space o n e space p e r s o n space s h a k e space h a n d s space w i t h space e v e r y space o t h e r p e r s o n comma space t h e n space i n space h o w space m a n y space h a n d space s h a k e s space h a p p e n space i n space t h e space p a r t y ? S o l u t i o n colon W h e n space t w o space p e r s o n s space s h a k e space h a n d s comma space i t space i s space c o u n t e d space a s space o n e space h a n d s h a k e. H e r e comma space t h e space o r d e r space i s space n o t space i m p o r tan t. H e n c e space i t space i s space a space c o m b i n a t i o n. T h e space t o t a l space n u m b e r space o f space h a n d s h a k e s space i s space s a m e space a s space t h e space n u m b e r space o f space w a y s space o f space s s e l e c t i n g space 2 space p e r s o n s space a m o n g space 25 space p e r s o n s. H e n c e space t h e space r e q u i r e d space n u m b e r equals C presuperscript 25 subscript 2 equals fraction numerator 25 factorial over denominator 2 factorial open parentheses 25 minus 2 close parentheses factorial end fraction equals 300
Answered by Vimala Ramamurthy | 15 Sep, 2015, 10:25: AM

Concept Videos

Multiple Choice Questions Practice Test
Answered Unanswered My Questions My Answers
CBSE 11-science - Maths
if npr-1/a=npr/b=npr+1/c then the value of b square/a(b+c)
Asked by tharshini8456157 | 27 Nov, 2023, 10:32: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 11-science - Maths
the number of words which can be formed out of the letters of the word PARTICLE so that vowels occupy even place is
Asked by ismayilpmamu | 09 Apr, 2020, 10:10: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 11-science - Maths
How many words can be formed by taking 4 letters at a time out of the letters of the words MATHEMATICS? 
Asked by Kashifimam866 | 20 Feb, 2019, 05:58: AM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 11-science - Maths
Find the no. Of arrangements  of the letters of the  word Delhi if e always  comes before i.
Asked by Sh1989kishore | 22 Oct, 2018, 10:12: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 11-science - Maths
From a group of 15 cricket players, a team of 11 players is to be chosen. In how many ways can this be done?
Asked by Topperlearning User | 04 Jun, 2014, 01:23: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 11-science - Maths
In how many ways can 5 girls and 3 boys be seated in a row so that no two boys are together?
Asked by Topperlearning User | 13 Sep, 2016, 02:58: AM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 11-science - Maths
In how many ways can 9 persons sit around a table so that all shall not have the same neighbours in any two arrangements?
Asked by Topperlearning User | 04 Jun, 2014, 01:23: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 11-science - Maths
How many triangles can be obtained by joining 12 points, five of which are collinear?
Asked by Topperlearning User | 04 Jun, 2014, 01:23: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 11-science - Maths
A student has to answer 10 questions, choosing at least 4 from each of part A and part B. If there are 6 questions in Part A and in part B, in how many ways can the student choose 10 questions?
Asked by Topperlearning User | 04 Jun, 2014, 01:23: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 11-science - Maths
If 8 parallel lines in a plane are intersected by a family of 10 parallel lines. Find the number of parallelograms formed?
Asked by Topperlearning User | 04 Jun, 2014, 01:23: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
My Class Videos Tests ₹ Plans Ask a Doubt
Get Latest Study Material for Academic year 24-25 Click here
×