math
posted by James .
A hollow steel tube, 4 m long, has walls 5 mm thick and is open at each end. if the outer diameter is 41 cm, what's the inner diameter?

first convert 5 mm to cm
recall that 10 mm = 1 cm
thus 5 mm = 1/2 cm = 0.5 cm
then we subtract the thickness by the outer diameter:
41  2*0.5
41  1 = 40 cm
hope this helps~ :) 
thanks, it helped a lot

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