Answer:
the crocodile is longer
Explanation:
To compare the lengths directly, we need to convert them to the same units. It is convenient to express the length of the alligator in meters.
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The length of the alligator is ...
4000 mm = (4000 mm)×(1 cm)/(10 mm)×(1 m)/(100 cm)
= 4000/(10×100) m = 4 m . . . . length of an alligator
The crocodile is 6 m long; the alligator is 4 m long, so the crocodile is longer.