Q4.An urn contains 5 red and 5 black balls. A ball is drawn at random, its colour is noted and is returned to the urn. Moreover, 2 additional balls of the colour drawn are put in the urn and then a ball is drawn at random. The probability that the second ball drawn is red will be
Q5.A number x is chosen at random from the first 100 natural numbers. Let A be the event of numbers which satisfies [(x − 10)(x − 50)] / [x − 30 ] ≥ 0 , then P ( A) is
Q9.There are three events A, B and C of which one and only one can happen. If the odds are 7 to 4 against A and 5 to 3 against B, then odds against C is