Final answer:
The question relates to finding the probability of managers earning a total over $400,000, and the 90th percentile for an individual manager's salary and the sum of salaries for ten managers using statistical methods such as cumulative distribution functions or z-scores.
Step-by-step explanation:
The questions provided appear to be related to statistics, specifically regarding the calculation of probabilities and percentiles for managers' salaries. The notations such as ΣX likely represent the summation of random variables (X), which could be the salaries of individual managers. The term 'EX~' suggests finding the expected value or mean of a distribution. When asked to find the probability that the managers earn a total of over $400,000, one would typically use the cumulative distribution function or normal approximation if dealing with large sample sizes.
Similarly, to find the 90th percentile for an individual manager's salary or the sum of ten managers' salary, one would look at the cumulative distribution function and determine the value below which 90% of the sample lies. This involves calculating the z-score associated with the 90th percentile and then using the mean and standard deviation of the distribution to find the corresponding salary value.