50) The least count of an outside micro meter is 0.01 mm. The range of the micro meter is 75 to 100 mm. The barrel reading is 15.50 mm and the 10th thimble graduation coincides with the barrel datum line. The reading is

51) The form of thread in a saw tooth thread is

52) The taper in a taper pin reamer is

53) A hole is to be made on mild steel with a 12 mm diameter reamer. If the under size is 0.3 mm and ifthe oversize is 0.05 mm, what will be the diameter of the drill for drilling the hole before reaming?

54) The side of a regular hexagon is 10 mm. What is the across flat to flat of the hexagon?