No 7 & 8

7. If X -N(100,16), find: a) P(X > 104) (0.1587) b) P(X

7. a) 104) (0.1587) b) < 92) (0.2275) c) < 115) (0.9999) . The score of 6000 candidates in a certain examination are found to be approximately normal distributed with a mean of 55 and a standard deviation of 10. a) Ifa score of 75 or more is required for passing with distinction, estimates the number of grades with distinction. (137) b) If 70% of the candidate pass the examination, calculate the probability that from three candidates selected at random, only two candidates pass the examination (0.441) c) Calculate the probability that a candidate selected at random has a score between 45 and 65. (0.6826)