Suppose that, on average, electricians earn approximately u = $54,000 per year in the United States. Assume that the distribution for electricians' yearly earnings is normally distributed and that the standard deviation is o = $12,000. a) What is the probability that the average salary of four randomly selected electricians exceeds $60,000? Round your answer to four decimal places. b) What is the probability that the average salary of four randomly selected electricians is less than $50,000? Round your answer to four decimal places. c) What is the probability that the average salary of four randomly selected electricians is more than $50,000 but less than $60,000? Round your answer to four decimal places