4. For a portfolio of risks, all members' aggregate losses per year per exposure have a normal distribution with a standard deviation of 1000. For these risks, 60% have a mean of 2000, 30% have a mean of 3000, and 10% have a mean of 4000. A randomly selected risk had the following experience over 3 years: In year 1, there were 24 exposures with total losses of 24000. In year 2, there were 30 exposures with total losses of 36000. In year 3, there were 26 exposures with total losses of 38000. Determine the Bhlmann-Straub estimate of the mean ag- gregate loss per year per exposure for year 4. 4. For a portfolio of risks, all members' aggregate losses per year per exposure have a normal distribution with a standard deviation of 1000. For these risks, 60% have a mean of 2000, 30% have a mean of 3000, and 10% have a mean of 4000. A randomly selected risk had the following experience over 3 years: In year 1, there were 24 exposures with total losses of 24000. In year 2, there were 30 exposures with total losses of 36000. In year 3, there were 26 exposures with total losses of 38000. Determine the Bhlmann-Straub estimate of the mean ag- gregate loss per year per exposure for year 4