A surface is prepared specially for an application with the profile as shown in the figure.

The theoretical $${R_a}$$ value for this surface, in $$\mu m,$$ is _______________.

During the measurement of internal taper of a part using standard balls of diameter $$15$$ $$mm$$ and $$20$$ $$mm$$, the large ball is found to protrude by $$5$$ $$mm$$ $$\left( {{h_1}} \right)$$ and the top of small ball is found to be $$35$$ $$mm$$ $$\left( {{h_2}} \right)$$ below the top face of the gauge. The taper angle, in degree, is ________________.

The alignment test ''Spindle square with base plate'' is applied to the radial drilling machine. A dial indicator is fixed to the cylindrical spindle and the spindle is rotated to make the indicator touch the base plate at different points. The test inspects whether the

Cylindrical pins of $${25^{\matrix{ { + 0.020} \cr { + 0.010} \cr } }}\,\,mm$$ diameter are electroplated in a shop. Thickness of the plating is $$30 \pm 0.2$$ micron. Neglecting gage tolerances, the size of the $$GO$$ gage in $$mm$$ to inspect the plated components is