$4.$ Revisit the network again and consider that specific resources $($Resources A$,$ B$,$ C & D$)$ are used for each activity and must be scheduled such that only one resource can be allocated to work on an activity at a time. The resources are identified by color and letter. For example, blue cannot be scheduled to work on two activities simultaneously. How long would it take to complete the project with these resource constraints?$4.$ Revisit the network again and consider that specific resources $($Resources A$,$ B$,$ C & D$)$ are used for each activity and must be scheduled such that only one resource can be allocated to work on an activity at a time. The resources are identified by color and letter. For example, blue cannot be scheduled to work on two activities simultaneously. How long would it take to complete the project with these resource constraints?