The diameter , Say X , of a electric cable , is assumed to be continuous random variable with p.d.f : f(x)= 6x(1-x) , 0<=x<=1. (1) Check that the above is a P.D.F. (2) Obtain an expression for the c. d. f. ...

Out of 800 families with 4 children each, how many families would be expected to have (1) two boys 2 girls (2) at least one boy (3) no girl (4) at most two girls ? Assume equal probabilities for boys and girls ?