In an entrance test, there are multiple choice questions. There are four possible answers to each question, only one of which is correct. The probability that a student knows the answer to a question is 90%. If he gets the correct answer to a question, then the probability that he was guessing is

A fair coin is tossed 9 times. On each toss, a man predicts that the outcome will be heads. The probability that the number of successful predictions is strictly greater than the number of unsuccessful predictions is...

Let $F(x)$ be the cumulative distribution function (c.d.f.) of a continuous random variable $X$. If $F(b) = 0.7$ and $P(X > a) = 0.4$, then the value of $P(a < X < b)$ is ...

If the probabilities of a student succeeding in the entrance tests for institutes A, B and C are $0.6$, $0.5$ and $0.4$ respectively, while the probability of succeeding in both A and B is $0.3$, in both B and C is $0.2$, in both A and C is $0.2$, and in all three is $0.1$, then the probability that the student succeeds in exactly one of these tests is......