Proportion web quest

Research and find the following information: length of Blue whales, fleas, and the diameter of the Earth; Use five feet five inches for an average height (length) of humans.
Calculate the following proportions (written as analogies) - humans:whales::fleas:???? and Blue whales:Earth::fleas:????
What would be the diameter of a planet if the largest creature that lived on it was a flea, and the proportion was the same as the ratio of the Blue Whale (our largest creature) to Earth?