The answer is 2,075. Please I need the solution step by step.

The annual loss of an individual policy is distributed as G(4,B), where the mean of the distribution of is 600. A randomly selected policy had losses of 1,400 in Year 1 and 1,900 in Year 2. Loss data for Year 3 were misfiled and the Bhlmann credibility estimate of the expected loss for the selected policy in Year 4 based on the data for Years 1 and 2 was 1,800. The loss for the selected policy in Year 3, however, was found later to be 2,763. Determine the Bhlmann credibility estimate of the expected loss for the selected policy in Year 4 based on the data of Years 1, 2, and 3. The annual loss of an individual policy is distributed as G(4,B), where the mean of the distribution of is 600. A randomly selected policy had losses of 1,400 in Year 1 and 1,900 in Year 2. Loss data for Year 3 were misfiled and the Bhlmann credibility estimate of the expected loss for the selected policy in Year 4 based on the data for Years 1 and 2 was 1,800. The loss for the selected policy in Year 3, however, was found later to be 2,763. Determine the Bhlmann credibility estimate of the expected loss for the selected policy in Year 4 based on the data of Years 1, 2, and 3