Re: JNU Q

Posted by Sinistral on May 15, 2013; 11:03am
URL: http://discussion-forum.276.s1.nabble.com/JNU-Q-tp7580714p7580721.html

using definition of median:
P(x<=m)>= 1/2 where m is median
so P(x<=10)>= 1/2

now we need to find:
P(X>=12)=1-P(X<=12)
             =1-[P(x<=10) + P(10<X<=12)]
             <= 1-[1/2 + P(10<X<=12)]  using median inequality
P(X>=12) <= 1/2 -  P(10<X<=12)]
we know that mean = 12 so P(10<X<=12)] will never be equal to zero.
hence   P(X>=12) < 0.5
option (b)