Question

      4   students in a class , 1 girl 3 boys . 1 student goes to the board to solve a   problem, first student goes back to seat then another student goes to the   board to solve another problem. find the probability that 2 boys go to the   board   1.Probability   of 2 girls go to the board ,   2. The   probability of a girl and a boy go to the board   3. First a boy   then a girl goes to the board