document.write( "Question 59211: please helps in this
\n" ); document.write( "let the pdf f(x) be positive at x=-1,0,1 and zero else where
\n" ); document.write( "1. if f(0) = 0.25 , find E(x^2)
\n" ); document.write( "2. if f(0) = 0.25 and if E(X) =0.25 , determine f(-1) and f(1)\r
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Algebra.Com's Answer #40746 by stanbon(75887)\"\" \"About 
You can put this solution on YOUR website!
let the pdf f(x) be positive at x=-1,0,1 and zero else where
\n" ); document.write( "1. if f(0) = 0.25 , find E(x^2)
\n" ); document.write( "Let f(-1)=x
\n" ); document.write( "The f(1)=0.75-x
\n" ); document.write( "E(X^2)=(0^2)*0.25+(-1)^2*x+(1)^2*(0.75-x)
\n" ); document.write( "E(X^2)=0+x+(0.75-x)
\n" ); document.write( "=0.75
\n" ); document.write( "------------
\n" ); document.write( "2. if f(0) = 0.25 and if E(X) =0.25 , determine f(-1) and f(1)
\n" ); document.write( "Let f(-1)=x
\n" ); document.write( "Then f(1)=(0.75-x)
\n" ); document.write( "E(X)=0*0.25+(-1)x+(1)(0.75-x)=0.25
\n" ); document.write( "-x+0.75-x=0.25
\n" ); document.write( "-2x=-0.5
\n" ); document.write( "x=0.25
\n" ); document.write( "So, f(-1)=x=0.25
\n" ); document.write( "f(1)=(0.75-x)=0.75-0.25=0.50
\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H. \n" ); document.write( "
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