Consider the following Linear Programming problem $$(LLP)$$

Maximize: $$Z = 3{x_1} + 2{x_2}$$
$$\,\,$$ Subject $$\,\,$$ to
$$\eqalign{ & \,\,\,\,\,\,\,{x_1} \le 4 \cr & \,\,\,\,\,\,\,{x_2} \le 6 \cr & 3{x_1} + 2{x_2} \le 18 \cr & {x_1} \ge 0,\,\,{x_2} \ge 0 \cr} $$

Six jobs arrived in a sequence as given below:

Average flow time (in days) for the above jobs using Shortest Processing Time rule is

A forged steel link with uniform diameter of $$30mm$$ at the centre is subjected to an axial force that varies from $$40kN$$ in compression to $$160kN$$ in tension. The tensile $$\left( {{S_U}} \right),$$ yield $$\left( {{S_y}} \right)$$ and corrected endurance $$\left( {{S_e}} \right)$$ strengths of the steel material are $$600MPa, 420MPa$$ and $$240MPa$$ respectively. The factor of safety against fatigue endurance as per Soderberg’s criterion is

A $${20^ \circ }$$ full depth involute spur pinion of $$4mm$$ module and $$21$$ teeth is to transmit $$15kW$$ at $$960rpm.$$ Its face width is $$25mm.$$

Given that the tooth geometry factor is $$0.32$$ and the combined effect of dynamic load and allied factors intensifying the stress is $$1.5;$$ the minimum allowable stress (in $$MPa$$) for the gear material is