Question 44741
A trough, in the form of an open rectangular box, is 1.85 m long, 45 cm wide and 28 cm deep externally. If the trough is made of wood 2.5 cm thick, find, in cubic centimetres, the volume of wood used. 
EXTERNAL DIMENSIONS 
L=1.85 M =185 CM.
B=45 CM
H=28 CM
OPEN AT TOP.
EXTERNAL VOLUME OF BOX =LBH=185*45*28=233100 CC
INTERNAL DIMENSIONS
WOOD THICKNESS=2.5 CM
L'=185-2*2.5=180 CM
B'=45-2*2.5=40 CM
H'=28-1*2.5=25.5 CM...SINCE THE BOX IS OPEN AT TOP
INTERNAL VOLUME OF BOX =L'*B'*H'=180*40*25.5=183600 CC
HENCE VOLUME OF WOOD =233100-183600=49500 CC