In a numerical control $$(NC)$$ machine positioning system, the measures of precision are expressed by considering a single axis as shown in the Figure.

If $$\sigma $$ is standard deviation of the error distribution, the $$L$$, $$M$$ and $$N$$ are

The preparatory and miscellaneous codes used in $$CNC$$ part programming and the functions are given in the Table

The correct combination of code and the respective function is

A schematic diagram of peripheral milling is shown in the Figure.

If $$t$$ is the depth of cut and $$d$$ is the diameter of the milling cutter, then the length of approach $$\left( {la} \right)$$ is expressed as

In a machining operation with turning tool, the tool life $$(T)$$ is related to cutting speed $$v$$ $$(m/s),$$ feed $$f(mm)$$ and depth of cut $$d(mm)$$ as $$$T = C\,v{\,^{ - 2.5}}\,{f^{ - 0.9}}\,{d^{ - 0.15}}$$$
where, $$C$$ is a constant. The suggested values for the cutting parameters are: $$V=1.5$$ $$m/s,$$ $$f=0.25$$ $$mm$$ and $$d=3$$ $$mm$$ for normal rough turning. If the operation is performed at twice the cutting speed and the other parameters remain unchanged, the corresponding percentage change in tool life is ______________.