1. 

   studyc Member

   Hi,
   
   In the solutions to the question it states 2x[P(Z<0.63246)-0.5]
   
   Why do we minus the 0.5 here?
   
   Thanks

    

   studyc, Apr 25, 2014

   #1
2. 

   John Lee ActEd Tutor Staff Member

   Because it means when multiplied out we get 2P(Z<0.63246) - 1
   which is a rearrangement of:
   
   P(-0.63246 < Z < 0.63246) = P(Z < 0.63246) - P(Z < -0.63246)
   
   = P(Z < 0.63246) - [1 - P(Z < 0.63246)]

    

   John Lee, Apr 28, 2014

   #2

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