As a project manager, you are aware that estimating schedule activity costs involves developing an approximation of the costs of the resources needed to complete each schedule activity. In approximating costs, the estimator considers the possible causes of variation of the cost estimates, including risks. Cost estimating includes identifying and considering various costing alternatives. For example, in most application areas, additional work during a design phase is widely held to have the potential for reducing the cost of the execution and product operations. The cost estimating process considers whether the expected savings can offset the cost of additional design work. Cost estimates are generally expressed in units of currency to facilitate comparisons both within and across projects. Cost estimates can also benefit from refinement during the course of the project to reflect on the additional detail available. For your project, which is in the initial phases, your team suggested a rough order of magnitude estimate—this could be in the range of （）.
A．-75% to+125%
B．-50% to+100%
C．-25% to+50%
D．None of the above
参考答案：B
解析：
作为项目经理, 你意识到估计进度活动成本包括完成评估每一进度活动所需的资源成本的近似值。在近似成本中, 评估者认为成本估计出现偏差的原因包括风险。成本估算包括识别和考虑不同的成本选择。例如: 在多数应用领域内, 附加工作在设计阶段被广泛运用以潜在地减少执行和生产成本, 成本估算过程考虑的是预期的节省能否抵消额外的设计工作的成本。成本估算一般用货币单位表示以方便项目内和项目问的比较。成本估计也有益于项目过程的精细, 反映在尽可能的附加细节中。对你的项目而言, 在启动阶段, 你的团队建议进行一个量级估算, 该估算的大概准确范围为 ______ 。 A) -75%至+125% B) -50%至+100% C) -25%至+50% D) 以上都不正确 抓关键语句，最后一句，一个项目在启动阶段进行的是量级估算，准确范围是-50%～100%。