I'm trying to figure out how the answer is 116,250 bricks! This is from an army mathematics paper. Your help will be much appreciated. Thank you.
Q.
How many bricks each of dimensions 15 cm x 10 cm x 8 cm are required to construct a wall 35 m long, 1.5 m side and 2 m high with two windows each 1.5 m x 4 m?
My answer.
How many bricks are required to build the wall without the windows (i.e holes)?
(35/0.15)*(1.5/0.1)*(2/0.08) = 87,500
How many of these bricks fill the necessary window space (how many are used to fill the holes)?
2*(4/0.08)*(1.5/0.1)*(1.5/0.15) = 15,000
So how many bricks are required to build the wall with the windows?
87,500 - 15,000 = 72,500 bricks.
How was 116,250 obtained?
Q.
How many bricks each of dimensions 15 cm x 10 cm x 8 cm are required to construct a wall 35 m long, 1.5 m side and 2 m high with two windows each 1.5 m x 4 m?
My answer.
How many bricks are required to build the wall without the windows (i.e holes)?
(35/0.15)*(1.5/0.1)*(2/0.08) = 87,500
How many of these bricks fill the necessary window space (how many are used to fill the holes)?
2*(4/0.08)*(1.5/0.1)*(1.5/0.15) = 15,000
So how many bricks are required to build the wall with the windows?
87,500 - 15,000 = 72,500 bricks.
How was 116,250 obtained?
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For what it is worth, it looks to me like you did it correctly. I don't know where 116,250 comes from.
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one brick:
Vb = 0.15*0.1*0.08 = 0.0012 mc
Vwall = 35*1.5*2 = 105 mc
Vwindows = 2*(1.5*1.5*4) = 9 mc
Vwall effective = Vwall - V windows = 96 mc
Nbricks = Vwall effective / Vbrick = 80,000 mc
Maybe the answer is 116,250 for army funding reasons :-)
Vb = 0.15*0.1*0.08 = 0.0012 mc
Vwall = 35*1.5*2 = 105 mc
Vwindows = 2*(1.5*1.5*4) = 9 mc
Vwall effective = Vwall - V windows = 96 mc
Nbricks = Vwall effective / Vbrick = 80,000 mc
Maybe the answer is 116,250 for army funding reasons :-)