The time taken to drill a hole through a 25 mm thick plate

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The time taken to drill a hole through a 25 mm thick plate with the drill rotating at 300 rpm and moving at a feed rate of 0.25 mm/rev is

1. 10 sec
2. 20 sec
3. 60 sec
4. 100 sec

Correct Option: B

T =	L	=	25100	=	1	min
	fN		0.25 × 300		3

T = 20 sec