It is necessary to redesign a rectangular channel in such a way that a section with the highest possible hydraulic efficiency is obtained. The configuration of the original channel measures $4m$ wide and $1m$ high. For cost reasons, the same amount of concrete lining should be maintained in the redesign. Calculate the new dimensions of the channel and the probable increase in flow.

Observation: your answers must be clearly justified.

Apply valid procedures and find the correct answer: $100\%$

Apply valid procedures and almost find the correct answer: $80\%$

Correctly proposes all valid procedures and develops without reaching the final answer: $50\%$

Correctly proposes all valid procedures without developing more than the approach: $20\%$

Presents the correct answer without a correct procedure: $0\%$

Does something that does not correspond or leaves it blank: $0\%$