Chiquita and the rhonda are each building a snowman. rhonda tells chiquita that she is making each of her 3 balls of snow 20% smaller than the one below it. rhonda starts by making the base ball with a diameter of 20 inches. if she reduces the diameter by 20% each time she makes a new ball, what is the diameter of the third ball she makes (the ball for the snowman's head)? express your answer as a decimal to the nearest tenth.