2008 q 51, 2005 q 23 and 2004 q 30

[Kamal]

q 51) Should'nt det A not equal to zero ensure a solution?

q 23) I have worked it out like this

We will get the series as 2*3/4 + 4*3/4*1/4 + 8*1/4*1/4*3/4..........
                                  = 3/2+3/4+3/8.....
                                   =3[1/2+1/4....]
                                 = 3*2 =6

Please help

[Khushboo]

Ans -30  2004 paper
          P(x2>1) = P(x>1 or X<-1)
                     = P(x>1) + P(x<-1)
                     = P+P = 2P
          P(y3 >1)= P(y>1) = p
  Therefore, P(x2>1 and y3 >1) = 2P.P = 2p2

[Khushboo]

Ans- 23 2005 paper
       As series r correct bt there is a mistake in ur calculation.
                                  = 2*3/4 + 4*3/4*1/4 + 8*1/4*1/4*3/4..........
                                  = 3/2+3/4+3/8.....
                                  = 3[1/2+1/4......]            
                                  = 3[1/2 / 1-1/2 ]
                                  = 3[1/2 / 1/2]
                                  = 3

[Amit Goyal]

Det A not equal to 0 ensure a solution only when A is a square matrix. No such information is given.

[Amit Goyal]

Thanks Khushboo, you earn 40 points for two right answers.