The diameter of a recessed ring was measured by using two spherical balls of diameter $${d_2} = 60mm$$ and $${d_1} = 40mm$$ as shown in the figure.

The distance $${H_2} = 35.55\,\,mm$$ and $${H_1} = 20.55\,\,mm$$. The diameter ($$D,$$ in $$mm$$) of the ring gauge is __________________.

For the given assembly : $$25$$ $$H7/g8,$$ match Group $$A$$ with Group $$B$$

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

A taper hole is inspected using a $$CMM,$$ with a probe of $$2mm$$ diameter. At a height, $$Z=10mm$$ from the bottom, $$5$$ points are touched and a diameter of circle (not compensated for probe size) is obtained as $$20mm.$$ similarly, a $$40mm$$ diameter is btained at a height $$Z=40mm.$$ The smaller diameter (in $$mm$$) of hole at $$Z=0$$ is