In an examination, a student can choose the order in which two questions (QuesA and QuesB) must be attempted.
- If the first question is answered wrong, the student gets zero marks.
- If the first question is answered correctly and the second question is not answered correctly, the student gets the marks only for the first question.
- If both the questions are answered correctly, the student gets the sum of the marks of the two questions.
The following table shows the probability of correctly answering a question and the marks of the question respectively.
question | Probability of answering correctly | marks |
QuesA | 0.8 | 10 |
QuesB | 0.5 | 20 |
Assuming that the student always wants to maximize her expected marks in the examination, in which order should she attempt the questions and what is the expected marks for that order (assume that the questions are independent)?
Consider the two statements.
S1 : There exist random variables X and Y such that
(E[X - E(X)) (Y - E(Y))])2 > Var[X] Var[Y]
S2 : For all random variables X and Y,
Cov[X, Y] = E [|X - E[X]| |Y - E[Y]|]
Which one of the following choices is correct?