A lens with and index of 3.0 and 10 mm thick has a front convex radius of 200 mm and a back convex radius of 50 mm. 

1.What is the lens focal length?
2.What are the vertex to principle plane distances?
3.What is the hiatus thickness
4.For a 200 mm object distance (object to first principle plane), what is the image distance from the last vertex?
5.If the object space is water, where are the nodal points?

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