# PERMUTATION & COMBINATION | IIT JEE CONCEPTS | Part 8 | JEE Advanced 2015 | BOX + GAP Method - Videos

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In this video, we will learn some very important concepts of arrangement by taking different cases in which some objects are separated or consecutive or both separated as well as consecutive. We will learn how we can apply both BOX METHOD and GAP METHOD together.

Questions Discussed
Let n be the number of ways in which 5 boys and 5 girls can stand in a queue in such a way that all the girls stand consecutively in the queue. Let m be the number of ways in which 5 boys and 5 girls can stand in a queue in such a way that exactly four girls stand consecutively in the queue. Then the value of m/n is

Four extra variations of the above question are also discussed
5 boys and 5 girls can stand in a queue in such a way that
(i) girls are separated from each other (or) No two girls are together
(ii) all five girls are separated from each other (or) No all girls are together
(iii) boys and girls are alternate (or) Boys as well as Girls are separated (or) Every girl follow a boy and every boy follow a girl
(iii) boys and girls are alternate and a particular boy B1 and girl G1 are always together

TRY YOURSELF Questions
4 boys and 4 girls are seated in a line. Find the number of ways so that:
(i) No two girls are together
(ii) Not all girls are together or atleast one girl is separated from the rest of girls
(iii) Boy and girls are alternate or boys as well as girls are separated or every girl follow the boy and every boy follow the girl
(iv) Boy and girls sit alternate if a particular boy B1, G1 are never adjacent to each other in any arrangement
(v) If these 8 happens to be 4 married couples such that these couples sit together
Answers: (i) 2880 (ii) 37440 (iii) 1152 (iv) 648 (v) 384

Permutation and Combination IIT JEE Concepts Playlist Link

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Permutation and combination IIT JEE Main + Advanced, Permutation and Combination IIT JEE Mathematics, Concept of Arrangement, Number of ways to arrange n different objects in n places, Permutation and Combination IIT JEE Questions, counting using Permutations, arranging n object in n places such the r objects are always together, number of way to arrange such that a number of objects are always consecutive, Number of ways to arrange identical objects, number of way to arrange such that a number of objects are always separated, no two girls are together, no two vowels are together, no two boys are together, no two consonants are together
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