A product made in two factories $$P$$ and $$Q,$$ is transported to two destinations, $$R$$ and $$S.$$ The per unit costs of transportation (in Rupees) from factories to destinations are as per the following matrix.

Factory $$P$$ produces $$7$$ units and factory $$Q$$ produces $$9$$ units of the product. Each destination requires $$8$$ units. If the north-west corner method provides the total transportation cost as $$X$$ (in Rupees) and the optimized (the minimum) total transportation cost $$Y$$ (in Rupees), then $$(X$$-$$Y),$$ in Rupees, is

Maximize $$\,\,\,\,\,\,\,\,\,Z = 5{x_1} + 3{x_2}$$
Subject to $$\,\,\,\,\,\,\,\,\,\,{x_1} + 2{x_2} \le 10,$$
$$\eqalign{ & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,{x_1} - {x_2} \le 8, \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,{x_1},{x_2} \ge 0 \cr} $$

In the starting simplex tableau, $${x_1}$$ and $${x_2}$$ are non-basic variables and the value of $$Z$$ is zero. The value of $$Z$$ in the next simplex tableau is __________________.

A single – plate clutch has a friction disc with inner and outer radii of $$20mm$$ and $$40$$ $$mm,$$ respectively. The friction lining in the disc is made in such a way that the coefficient of friction $$\mu $$ varies radially as $$ = 0.01\,r,$$ where $$r$$ is in $$mm.$$ The clutch needs to transmit a friction torque of $$18.85$$ $$kN.mm.$$ As per uniform pressure theory, the pressure (in $$MPa$$) on the disc is ___________________.

A machine component made of a ductile material is subjected to a variable loading with $${\sigma _{\min }} = - 50MPa$$ and $${\sigma _{\max }} = 50MPa.$$ If the corrected endurance limit and the yield strength for the material are $$\sigma {'_e}$$ $$100MPa$$ and $${\sigma _y} = 300MPa,$$ respectively, the factor of safety is __________.