Activities A to K are required to complete a project. The time estimates and the immediate predecessors of these activities are given in the table. If the project is to be completed in the minimum possible time, the latest finish time for the activity G is ______ hours.

$$ \begin{array}{|c|c|c|} \hline \text { Activity } & \text { Time (hours) } & \text { Immediate predecessors } \\ \hline \text { A } & 2 & - \\ \hline \text { B } & 3 & - \\ \hline \text { C } & 2 & - \\ \hline \text { D } & 4 & \text { A } \\ \hline \text { E } & 5 & \text { B } \\ \hline \text { F } & 4 & \text { B } \\ \hline \text { G } & 3 & \text { C } \\ \hline \text { H } & 10 & \text { D, E } \\ \hline \text { I } & 5 & \text { F } \\ \hline \text { J } & 8 & \text { G } \\ \hline \text { K } & 3 & \text { H, I, J } \\ \hline \end{array} $$

An assignment problem is solved to minimize the total processing time of four jobs (1, 2, 3 and 4) on four different machines such that each job is processed exactly by one machine and each machine processes exactly one job. The minimum total processing time is found to be 500 minutes. Due to a change in design, the processing time of Job 4 on each machine has increased by 20 minutes. The revised minimum total processing time will be ________ minutes (in integer).

The product structure diagram shows the number of different components required at each level to produce one unit of the final product P. If there are 50 units of on hand inventory of component A, the number of additional units of component A needed to produce 10 units of product P is _________ (in integer).

A square threaded screw is used to lift a load W by applying a force F. Efficiency of square threaded screw is expressed as