@mihanni21 ,
There are two equally likely outcomes for each child (boy or girl). Therefore, there are 2*2*2*2=16 possible outcomes:
bbbb
bbbg
bbgb
etc.
Using the table of 16 possible outcomes, determine how many satisfy each question, then divide by the total number of possible outcomes to get the probability. Hint: One of the questions can't be answered with the data that is given.