On a multiple choice examination with three possible answers for each of the five questions what is the probability that a candidate would get four or more correct answers just by guessing?

In answering a question on a multiple choice test,a student either knows the answer or guesses. Let 3/4 be the probability that he knows the answer and 1/4 be the probability that he guesses. Assuming that a student who guesses at the answer will be correct with probability 1/4. What is the probability that the studdent knows the answer given that he answered it correctly?

In an examination 20 question of true false type are asked suppose a student tosses a fair coin to determine his answer to each question if the coins falls heads he answers true if it falls tail he answers false find the probability thet he answers at least 12 question correctly.

An examination has 25 questions. Each correct answer gets 2 marks, for each wrong answer 1 mark is taken away. If answer is not written no marks will get. In this examination if one scored 6 answers are correct and 19 answers are wrong and other 5 answers are correct and 15 wrong and 5 are not answered. Who got more marks?

According to Bohr's theory, E_(n)= Total energy, K_(n) = Kinetic energy, V_(n) =Potential energy, r_(n/) = Radius of orbit. Each of these questions contains two statements: Statement 1 and Statement2. Each of these questions has four alternative choices, only one of which is the correct answer.