a fixed sum meaning in Chinese

固定数目

The six sigma black belt should be able to compute the value of money held or invested over time , including present value and future value of a fixed sum
6西格玛黑带应能计算出所持资金或者已投资金的价值，包括现值和未来价值的固定总和。
Why does the government not use a fixed sum of capital investment instead of granting land rights ? the final cost of granting land rights is much more uncertain and it can far exceeds the present estimated values in a few years time
政府为何不用定额注资的办法，而选用成本更难预计最后有可能远高于现时估值的批地权方式作出注资？