15) The grain size of a grinding wheel is indicated by number. Which range of grain size reffered to 'very fine'?

16) Due to continuous use the grinding wheel of an offhand grinder is glazed locally. What tool will you use to rectify these defects?

17) The tooth thickness of a rack is measured by

18) A shaft is turned in one finish cut. Which one of the following parameter will directly influence the machining time?

19) Convert 4/5 into decimal