Question 476505
Kitchen Boxes = 4
Bedroom Boxes=6
Total Boxes=10

Use   
 nCr=n! /(n-r)! r!

 4 Boxes can be placed out of 10 Boxes 	= 10C4
                                        = 10!/(10-4)!4!
                                        = 10*9*8*7*6!/6! (4*3*2*1)
					=5040/24
					=210 ways

1 Kitchen  box can be placed out of 4	=  4C1
					= 4!/(4-1)! 1!
					= 4!/3!1!
					= 4*3!/3!
					= 4 ways
3 Bedroom boxes can be placed out of 6	=  6C3
					= 6!/(6-3)! 3!
					= 6!/3!3!
					= 6*5*4*3!/3! 3*2*1
					= 6*5*4*/ 3*2*1
					=120/6
					=20 ways
P(1 kitchen box and 3 Bedroom boxes)	= (4C1*6C3)/10C4
					= (4*20)/210
					=80/210
					=8/21
					=0.3809