## Shubham Agrawal is teaching live on Unacademy Plus

Permutation and Combination

About Me Shubham Agrawal IIT Roorkee 2013 graduate IIM Dropout SBI PO under 100 ranker (dropout) Left job to pursue my passion- Education

Factorial Denoted as n! or h

Concept 21-2 2) 6 41 24 6) = 720 75040

Concept 0!

Questions In a class there are 10 boys and 8 girls. The class teacher wants to select a student for monitor of the class. In how many ways the class teacher can make this selection?

Questions Q. In a class there are 10 boys and 8 girls. The class teacher wants to select a student for monitor of the class. In how many ways the class teacher can make this selection? ophons -12

Questions In a class there are 2 boys and 2 girls. The teacher wants to select a boy and a girl to represent the class in a function. In how many ways can the teacher make this selection?

Questions Q. In a class there are 2 boys and 2 girls. The teacher wants to select a boy and a girl to represent the class in a function. In how many ways can the teacher make this selection? ns 22-4 Pr A-D

Questions In a class there are 10 boys and 8 girls. The teacher wants to select a boy and a girl to represent the class in a function. In how many ways can the teacher make this selection?

Questions In a class there are 10 boys and 8 girls. The teacher wants to select a boy and a girl to represent the class in a function. In how many ways can the teacher make this selection? 1O

Questions There are 6 multiple choice questions in an examination. How many sequences of answers are possible, if the first three questions have 4 choices each and the next three have 5 choices each?

Questions Five persons entered a lift cabin on the ground floor of an 8-floor house. Suppose that each of them can leave the cabin independently at any floor beginning with the first. What is the total number of ways in which each of the five persons can leave the cabin at any of the 7 floors?

Questions The number of four digit numbers is?

Questions Q. The number of four digit numbers with distinct digits is?

Questions In how many ways can 5 people sit in a row?

Questions Q. In how many ways can 5 people sit in a row? 5 432

Questions In how many ways can 5 people sit in a circle?

Concept Number of ways in which "n" things can be arranged in a circle is (n-1)!

Concept Number of ways in which "n'" things can be arranged in a circle is (n-1)!/2 if clockwise and anticlockwise are considered same

Concept 3-2 2 2 2 ne Neg 2.

Questions Q. In how many ways can 5 people sit in a circle such that none has the same neighbous ? : - 2 2

Questions In how many ways can 5 boys and 5 girls be seated at a round table no two girls may be together?

Arrangement of letters

Questions Q. In how many distinguishable ways can the letters in BANANA be written? LANAN A

Questions How many 4 digits number (repetition is not allowed) can be made by using digits 1-7 if 4 will always be there in the number

Questions Q. How many 4 digits number (repetition is not allowed) can be made by using digits 1-7 if 4 will always be there in the number?. 4

String Theory

Questions Q. In how many ways can we arrange the five vowels, a, e, i, o & u if: (i) two of the vowels e and i are always together. (ii) two of the vowels e and i are never together.

Questions In how many ways can 5 prizes be given away to 4 boys when each boy is eligible for all the prizes?

Questions How many numbers of 3 digits can be formed with the digits 0, 1, 2, 3, 4, 5 when digits may be repeated? 3.3 atZT CTTU Tad 0,1, 2, 3, 4, 5

Questions Find the number of ways in which 18 different beads can be arranged to form a necklace.

Questions In a cricket tournament 5 matches were played, then in how many ways resu It can be declared?

Questions Q. In a cricket tournament 5 matches were played then in how many ways result can be declared? 22 22 32

Questions There are 10 lamps in a hall. Each of them can be switched on independently. The number of ways in which the hall can be illuminated is

Questions Q. There are 10 lamps in a hall. Each of them can be switched on hall can be illuminated is independently. The number of ways in which the llnion 2.

Questions In a class of 25 students, find the total number of ways to select two representative, (i) if a particular person will never be selected. (ii) if a particular person is always there. 24 2 23 x 24-23x 12 2

Questions In a class of 25 students,find the total number of ways to select two representative, () if a particular person will never be selected. (ii) if a particular person is always there. 2 2 24-24

Questions In a party, every person shakes his hand with every other person only once. If total number of handshakes is 210, then find the number of persons.