Find an explicit formula for h(n)

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Apinhole camera is made out of a light-tight box with a piece of film attached to one side and pinhole on the opposite side. the optimum diameter d(in millimeters) of the pinhole can be modeled by d=1.9[ (5.5 x 10^-4) l) ] ^1/2, where l is the length of the camera box (in millimeters). what is the optimum diameter for a pinhole camera if the camera box has a length of 10 centimeters

The cost of using a service is $0.25 per min. what equation correctly represents the total cost c, in dollars, for d days of use?

Aclothing designer is selecting models to walk the runway for her fashion show. the clothes she designed require each model’s height to be no more than y inches from 5 feet 10 inches, or 70 inches. which graph could be used to determine the possible variance levels that would result in an acceptable height, x?