Question

in how many ways can 12 boys be seated in 10 different chairs in a row so that 2 particular boys always have a seat

Answer 1

here is ur ans. .....
so there are 3628800 possible arrangements.

if u can't understand u can ask me ....

Answer 2

$\mathfrak{\huge\underline{Answer:}}$

total arrangements=10*9*8*7*6*5*4*3 = 1814400. final arrangement will also include arrange of those two particular boys ies 181400*2=362800

Let these 2 persons be A & B.

Number of ways in which they can be arranged in a circle where they stay together = 10! x 2!

where, 10! = number of ways of arranging (n-1) people, where N is 11 as A and B are grouped together.

2! = ways of arranging A and B.

Total ways of arrangement = 11!

Thus the probability = (10! x 2!) / 11!