Coal is carried from a rrrine in West Virginia to a power plant in New York in hopper cars on a long train. The automatic hopper car loader is set to put 36 tons of coal in each car. The actualweights of coal loaded into each car are normally distributed with a mean jJ. = 36 tons and a standard deviation g = 0.8 tons.
(a) What is the probability that ONE car chosen at random will have -less than 35.5 tons of coal?
(b) What is the probability that 20 cars chosen at random will have a mean load weight x less than 35.5 tonsof coal?
(c) Suppose that the weight of coal in one car was less than 35.5 tons. Would that fact make you suspect that the loader had slipped out of adjustment? Suppose the weight of coal in 20 cars selected at random had an average x less than 35.5 tons, Would that fact make you suspect that the loader had slipped out of adjustment? Why?
2. To be licensed as a practical nurse, one must make a score in the-top 30% on the licensing exam. (15) The mean score of all strtdents tiling the exam is 79 with a standard deviation of 9 points and the scores are given in whole number values. What is the least score a student can make and be considered in the top 30%?