Infer two beams from their brightest and dimmest readings

A stable two-beam phase scan has maximum 49 W/m² and minimum 9 W/m². The beams have parallel polarization.

What is the ratio of the stronger beam intensity to the weaker one?

Organize the givens & assumptions

Imax = 49 W/m²
Imin = 9 W/m²

Same-frequency coherent beams, parallel polarization, same observation medium and unchanged individual detector intensities, unless the prompt explicitly averages phase.

A $4$
B $25/4$
C $5/2$
D $49/9$

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