1.A bag contains 21 coins. It is known that 10 of these have a head on both sides whereas the remaining 11 coins are fair. A coin is picked up at random from the bag and tossed. The probability that the toss results in a head is

2.A fair coin is tossed repeatedly. If tail appears on first four tosses, then the probability of head appearing on fifth toss equals

3.If on an average 2 ships in every 10, sinks. The probability that out of 5 ships expected to arrive, at least three will arrive safely, is

4.A bag contains 5 brown socks and 4 white socks. A man selects two socks from the bag without replacement. The probability that the selected socks will be of the same colour, is

5.The probability that a man can hit a target, is 3/4. He tries 5 times. The probability that he will hit the target at least 3 times, is