_______ and _________are two ways to calculate activity estimates.

PERT (Program Evaluation and Review Technique) and CPM (Critical Path Method) are two project management techniques used to calculate activity estimates. PERT is a statistical tool used to plan and control large projects, which involves breaking the project into tasks and estimating the minimum, most likely, and maximum times needed to complete each task. On the other hand, CPM is used to identify the longest path of planned activities to the end of the project and the earliest and latest that each activity can start and finish without making the project longer1.

References: = This information is verified using resources that discuss project schedule management according to the PMBOK Guide, which includes techniques like PERT and CPM for estimating activity durations1.