A three multiple choice question has 4 options. Choosing the correct option earns the student 3 marks. However choosing the wrong option incurs negative marks so that if a student chooses an option randomly, his expected score is 0. Suppose a student has successfully eliminated 2 incorrect options. His expected score if he chooses randomly among the remaining options is
a.1.00
b.1.50
c.00
d.3

• a. 1.00
  ¼ X 3 + ¾ X (p) = 0, whereas, ¼ and ¾ are probabilities of marking the right and wrong options respectively and 3 and p are the equivalent marks. From there, p = -1. Now if a student eliminates 2 wrong options, the probable score would be ½ X 3 + ½ X (-1) = 1
  
• 13 years agoHelpfull: Yes(14) No(0)
• since on selecting it randomly the student's expected score is 0 so its obvious that again on selecting among rest two randomly the score would be 0 only. hence (c) is correct.
  
• 13 years agoHelpfull: Yes(10) No(8)
• There are two possibilities only -> Correct Answer or Wrong Answer
  Let E be the expectation of the outome. There are four options. Probability of selecting any one = 1/4 = 0.25
  Then, E = 0.25*3 + 0.75*x = 0 (given)
  where x is the negative marks given to a wrong option selected
  Solving, we get x = -1
  Now, two incorrect options have been eliminated.
  So, E = 0.5*3 + 0.5*(-1) = 1
  Hence, option 1
• 11 years agoHelpfull: Yes(8) No(2)
• 3 question have 4 options,
  correct option 3 marks,
  wrong option negative mark.
  the student eliminate 2 incorrect options choose any one of the another option,
  if the student choose wrong answer means they got negative mark,
  the option not having the negative mark.
  so the student giving the right option..
  so expected score is 3.
  answer is option D
• 13 years agoHelpfull: Yes(2) No(19)
• in the question it clearly says that if option is chosen randomly,then the score is 0.
  so if he chooses randomly from the remaining 2 options,his score is 0.
• 8 years agoHelpfull: Yes(1) No(0)