For a 35mm camera, the equation 1/f=1/d+1/d represents the focal length (f) of the lens that is needed to produce a clear photograph. The distance from the lens to the film d1 must be adjusted according to the distance from the lens d0. If d1=x^2-4x-12 and d0=4x+8, what is 1/f?

Suppose babies born after a gestation period of 32 to 35 weeks have a mean weight of 25002500 grams and a standard deviation of 800800 grams while babies born after a gestation period of 40 weeks have a mean weight of 27002700 grams and a standard deviation of 385385 grams. if a 3232-week gestation period baby weighs 21252125 grams and a 4040-week gestation period baby weighs 23252325 grams, find the corresponding z-scores. which baby weighs lessless relative to the gestation period?