A multiple choice question paper has 4 options. For a correct answer, the student is awarded 5 marks. Negative marks are awarded for wrong attempts in such a manner that if the student randomly guesses the answers, his expected score is 0. If the student has eliminated two incorrect answer options, what is his expected score if he randomly guesses from the remaining options?
a)2.50 b)1.6 c)5 d) 0

• The Answer is 2.5
  The probability of getting a right answer is 1/2, since two incorrct options can be eliminated.
  Similarly the probability of getting a wrong answer is 1/2.
  Thus, in aggregate, the total probabilty of expected score corresponds with their marks are
  
  (5*1/2)+(0*1/2)=2.5
• 13 years agoHelpfull: Yes(10) No(2)
• Ans will be 1.6
  question paper has 4 options. For a correct answer, the student is awarded 5 marks and negative marks are awarded for wrong attempts.
  let x b the negetive marks.
  so, 5/4+ x/4+ x/4+ x/4 = 0
  x must be -5/3 to satisfy the eqution.
  
  two option are discarded,so total probability is-->
  
  5*1/2+x/2=5/2-5/(2*3)=5(26)=5/3=1.66
  
  
• 11 years agoHelpfull: Yes(2) No(1)
• Zero is the answer..
  5*1/4+x/4+x/4+x/4
  also x=0
  5*1/2+0*1/2 = 0
• 13 years agoHelpfull: Yes(1) No(6)
• answer is 0
  bcos he is randomly guessing & ifthe student randomly guesses the answerhis expected score is 0
• 12 years agoHelpfull: Yes(1) No(0)