You are taking pictures of the beach at sunset. Before the Sun sets, a shutter speed of 1/125 s at f/11 produces a properly exposed picture. Shortly after the Sun sets, however, your light meter indicates that the scene is only one third as bright as before. (a) If you don't change the aperture, what exact shutter speed will produce a picture with the same exposure? (b) If, instead, you keep the shutter speed at 1/125 s, what exact f-number will produce a picture with the same exposure? 2. f-number = focal length / Diameter of aperture 3. I'm not sure what the significance of the picture being 1/3 as bright after the sun sets is. But, I do know that when you change the shutter speed, you need to change the area of the aperture to compensate if you want to maintain the same exposure. Other than that, I don't know where to start on this problem. I would appreciate any help!