The largest eye ever to exist on Earth belonged to an extinct species of ichthyosaur, Temnodontosaurus platyodon. This creature had an eye that was 26.4 cm in diameter. It is estimated that this ichthyosaur also had a relatively large pupil, giving it an effective aperture setting of about ƒ/1.1.
(a) Assuming its pupil was one-third the diameter of the eye, what was the approximate focal length of the ichthyosaur's eye?
(b) When the ichthyosaur narrowed its pupil in bright light, did its ƒ-number increase or decrease? Explain.