Your camera determines the focal distance required for your picture to be in focus using the lens equation, 1/F-1/S=1/D, where the focal distance to the object from the lens (D) is related to the focal length (F) and the distance from the lens to the film (S). If an object is placed 8 cm from a lens with a focal length of 4 cm, how far from the lens is the image (film) formed?

You were told that the amount of time lapsed between consecutive trades on the new york stock exchange followed a normal distribution with a mean of 15 seconds. you were also told that the probability that the time lapsed between two consecutive trades to fall between 16 to 17 seconds was 13%. the probability that the time lapsed between two consecutive trades would fall below 13 seconds was 7%. what is the probability that the time lapsed between two consecutive trades will be between 14 and 15 seconds?