Permutations & Combinations - Questions & Discussions

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.Can someone help me out with the following problems with some clear and simple approcah to these qustions 4 balls are to be put in 5 boxes.in how many ways can this be done if a)Balls are similar and boxes are different b)balls are ...
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A girl has three library cards and seven books of her interest in the library of Mindworkzz, Of these books she would not like to borrow the D.L. book, unless t Quants book is also borrowed. In how many ways can she take the three books to be borrowed (a) 15 (b) 20 (c) 25 (2) 30 58. From a group of 12 dancers, five have to be taken for a show. Among them Radha and 5 Mohan decide either both of them would join or none of them would join. In how many ways can the 5 dancers be chosen? (a) 190 (b) 210 © 278 (d) 372

2 comments
Krazy_me
@Krazy_me  ·  3 karma

1) Say she doesn't need DL book, then she can choose in 6c3 ways = 20 ways Id she she chooses the DL book then in 5c1 ways = 5 ways Total = 20+5 = 25 ways

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Krazy_me
@Krazy_me  ·  3 karma

2) 10c5 ways when both (Radha and Mohan) are not chosen 10c5 ways = 252 ways and when both are chosen = 10c3ways = 120 ways => total = 372 ways

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Please help me out with the below scenario,

Suppose I have a set of duplicate numbers such as S={1,2,3,1,2,3}

and out of those I have to select 4 numbers such that their rearrangement is not counted.


For e.g in this case for selection 4 numbers

1,2,3,1

1,2,3,2

1,2,3,3

1,1,2,2

2,2,3,3

1,1,3,3


so total 6 cases are possible.


while selecting 5 numbers

1,2,3,1,2

1,2,3,1,3

1,2,3,2,3


only three cases are possible.


Can some please come up with a solution for the question and the set can be of any number with equal number of duplicates in it.


1 comment
prerak_bhandari
@prerak_bhandari  ·  1 karma

 guys please help me here with this 

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xat discution

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In how many ways can 14 Identical toys distributed among 3 boys so that each boy gets at least one toy and no two boy get the same number of toys?

78
60
24
120
6 likes25 answers
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Total number of three friends with moti, sumit and manky put together is 10.If the sum of a reciprocal of a number of bananas with the three friends is 1.What is the difference between the number of bananas with moti and sumit?

2
3
0
none of these
8 answers
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Can anyone share all the basic formulas needed for P&C?

And few basic examples and Few specific repeated difficult questions.?

It will be helpful. Thanks. 😃

Do a job that gets you a name or have a name that gets your job done.
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Five balls of different colors are to be placed in three different boxes such that each box gets at least 1 ball. What is maximum number of ways in which this can be done ?

ans 150 or 180

Arun Sharma Worked out example he has given it has 150 .. shouldn't it be 180 ?!!

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rockyxxxddd
@rockyxxxddd  ·  5 karma

Apply inclusive exclusive principle

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sudip12386
@sudip12386  ·  0 karma

150

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1) IxI+IyI+IzI=15- Total no. of integral solutions?

2) xyz=10^6- Total no. of natural no. solutions?

Can someone explain the approach to such questions please?

CAT 2015 93.6 IIFT 2015 94.27 SNAP 2015 98.56 NMAT 210
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rockyxxxddd
@rockyxxxddd  ·  5 karma

1) straight approach 4n^2+2=902

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rockyxxxddd
@rockyxxxddd  ·  5 karma

2. 13?

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How many ways can the letters of the word VARIETY Be arranged so that exactly two vowels are together? 

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sudip12386
@sudip12386  ·  0 karma

4320??

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khushiahuja12
@khushiahuja12  ·  0 karma

720

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