The Environmental Department monitors sulphur dioxide (SO2) emission of ABC powerplant every hour. Assume the concentration of SO2 from ABC powerplant is normal distributed. The powerplant claims that the average SO2 emission is 75 ppb (parts per billion) and the standard deviation is 0.75 ppb. The Environmental Department set the standard of SO2 concentration for all powerplants is 77 ppb. (a) Find the probability that the SO2 concentration of a randomly selected 5 marks hour between 74.34 ppb to 74.82 ppb. (b) Calculate the SO2 concentration interval for the middle 95% of the 5 marks emission and explain the result. (c) Find the probability that the powerplant will exhaust more than the 3 marks standard. (d) There are randomly selected 11 powerplants in this country with mean of 75.2 ppb and standard deviation of 0.4 ppb. (i) Construct a 90% confidence interval for the population mean 5 marks and interpret the result. (ii) Determine the assumption in d(i). 2 marks|