Arrowhead

It took Kevin 16 minutes to sharpen the entire edge (in red) of a large arrowhead. As pictured, 4 small arrowheads can be cut out of one large arrowhead. After cutting up the large arrow head into 4 small ones (that are each the same shape as the large arrowhead) how long will it take Kevin to re-sharpen all edges of all 4 of the small arrowheads?

Details and Assumptions

• Kevin sharpens at a steady rate along the length of the edges he works on.
• Even the original edges will need to be re-sharpened.