Help.

There are 20 children in the cast of a class play and 8 of the children are boys of the boys 4 have a speaking part in the play and of the girls 8 do not have a speaking part in the play if a child from the cast of the place chosen at random what is the probability that the child has a speaking part

If y varies directly as x2 and y=6 when x=6, find the constant of variation.

The distance between two points is 6.5cm and scale of map is 1: 1000 what's the distance between the two points