a common method for measuring

Question 1 (8 marks) A common method for measuring the size of a listed company is to use its market capitalization, which is computed by multiplying the number of stock shares by the price of a share of stock. The entire population of market capitalization values is known to follow the normal distribution with 2.28% of the market capitalization values over 900 billion and 15.87% of the market capitalization values below 300 billion. (a) Find the mean and standard deviation of the population distribution. (5 marks) (b) An investment portfolio is formed by randomly selecting 25 listed companies from the population. Find the probability that the total market capitalization value of all the selected companies is over 10,000 billion.