16.Three letters are written to different persons and corresponding addresses are written on three envelopes. However, letter are placed in envelopes without looking at the addresses. The probability that the letters go into right envelopes, is

17.In a game called odd man out, 4 persons toss a coin to decide who will buy refreshments for the entire group. A person who gets an outcome different from that of the rest of the members of the group is called the odd man out. The probability that there is a loser in any game is

18.The probability that a company executive will travel by train is 2/3 and that he will travel by plane is 1/5. The probability of his travelling by train or plane is

19.The probability that England wins a cricket match against India, is 1/3. If India and England play 3 test matches, the probability that India will win exactly 2 test matches, is

20.The probability that a non-leap year has 53 sunday is