Question

10Pr+1 : 11Pr = 30:11
please help me out

Answer 1

Please see the attachment

Answer 2

Answer:

Step-by-step explanation:

P(10,r+1):P(11:r)=30:11

P(10,r+1)/P(11,r)=30/11

10!/10!-(r+1)/11!/11!-r!=30/11

10!/(10-r-1)!/11!/(11-r)!=30/11

10!/(9-r)!/11!/(11-r)!=30/11

10!×(11-r)!/(9-r)!×11!=30/11

10!×(11-r)(10-r)(9-r)!/(9-r)!×11×10!=30/11

(11-r)(10-r)/11=30/11

(11-r)(10-r)=30

110-11r-10r+r²=30

110-21r+r²-30=0

r²-21r+80=0

r=-b±√b²-4ac/2a

=-(-21)±√(-21)²-4×1×80/2

=21±√441-320/2

=21±√121/2

=21±11/2

case(1):21+11/2

          = 32/2

         r=16

case(2):21-11/2  

           =10/2

         r=5