document.write( "Question 1150438: contractor plans to use four tractors to work on a project in a remote area. The
\n" ); document.write( "probability of a tractor functioning for a year without a break-down is known to be
\n" ); document.write( "80 %. If X denotes the number of tractors operating at the end of a year, determine the
\n" ); document.write( "probability mass and distribution functions of X. \n" ); document.write( "

Algebra.Com's Answer #772703 by Boreal(15235) $\"\"$ $\"About$

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The mean is xp=0.8*x
\n" ); document.write( "the variance is xp(1-p)=0.8*0.2*x=0.16x, and the sd is 0.4*sqrt(x) \n" ); document.write( "

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