16.Out of 800 families with 4 children each, the expected percentage of families having almost 2 girls , is

17.A man and his wife appear for an interview for two posts. The probability of the mans selection is 1/5and that of his wife selection is 1/7. The probability that at least one of them is selected, is

18.A problem in satististics is given to three students whose chances of solving it are 1/2, 1/3,1/4 respectively. The probability that the problem is solved is

19.A die is thrown 4 times. The probability of getting at most two 6 is

20.Two dice are thrown. The numbr of sample points in the sample space when six does not appear on any one side is