In entry number 3, the value in the Cost Amount (Actual) field is valued by average and therefore includes the erroneous posting of 1000.00. Accordingly, it becomes -433,33, which is an inflated cost amount. The calculation is 1300 / 3 = .- 433,33.
In entry number 5, the value of the Cost Amount (Actual) field for this entry is also inaccurate for the same reason.