the outer dimensions of a wooden box ae 10cm 8cm and 7cm. The thickness of the wood = 1cm. Cost of making the box if cost of wood = rs4 / cm3 = x. Find x.
Book's answer - 1280.
Is it wrong? Please help.
2007-02-22 03:59:28 · 6 answers · asked by mint 2 in Science & Mathematics ➔ Mathematics
Assume the box is with the lid
Ext Volume = 10 x 8 x 7 cm 3
= 560 cm 3
Coming to the int. dimension
Length will be reduced by 2 cm. Because the wood thickness is 1 cm and is coming to both sides Simillarly the breadth and height.
Then the int. volume is
= (10 - 2)(8 - 2 )(7 - 2 ) cm 3
=8 x 6 x 5 cm 3
= 240 cm 3
Difference bet. External Volume and Internal volume is = 560 - 240 cm 3
= 320 cm 3
Cost of timber Rs 4 /= per cm 3
Hence the total cost = Rs. 320 x 4
= Rs. 1280 /=
2007-02-22 09:12:10 · answer #1 · answered by brainy 4 · 0⤊ 0⤋
I get:
either a box with 5 sides at 8 x 7 (56cm3 x 5 x rs4)=1120
or a cube with 6 sides at 8 x 7 (56cm3 x 6 x rs4)=1344
2007-02-22 04:11:04 · answer #2 · answered by Super C 2 · 0⤊ 0⤋
The last line of your question is not clear. I don't understand what you mean by rs4. However, I think that what you have been asked to do probably involves calculating the volume of wood and then multiplying by the cost per cm3 to find the total cost. To find the volume of wood, calculate the volume as if it were solid. Then calculate the volume of air inside and subtract it from the previous value. This should be enough to get you started. Try to do it yourself now before looking at anyone's precise answer left here.
Follow up. If rs4 means 4 rands or some similar then the book answer is correct.
2007-02-22 04:11:13 · answer #3 · answered by Anonymous · 1⤊ 0⤋
outer volume=10*8*7=560cm cube
less inner volume =9*7*6=378
wood required=560-378=182 cubic cm
tatal cost=4*182=728
2007-02-22 04:27:19 · answer #4 · answered by Diksha A 3 · 0⤊ 0⤋
Hey the answer is right..
(10*8) be the area of the top & bottom sheets of box & as thickness is 1.
v1.)volume of sheets (top & bottom) = (10*8*1)*2 as, there are 2 sheets one on top & other at the bottom.
there fore v1.)=160cm^3
v2.) volume of sheets on its sides across length of 10 cm=
(10*(7-2))*2
(7-2) because thickness of top & bottom sheets is 1 cm each.
Therefore, v2.)= (10*5*2) = 100 cm^3
& volume of sheets on sides along breadth of 8 cm
v3.) = ( (7-2) * (8-2) ) *2
(8-2) because thickness of sheets on the sides is alreadry there..
v3.)= (5*6*2) = 60 cm^3
Therefore total volume v= v1.+v2.+ v3.=160+100+60
v=320cm^3
cost of 1cm^3 is rs.4 . there fore total cost is = 320*4
=Rs.1280
The book ans. is right
Its difficult to imagine it.. wish i could have drawn the diagram & made you understood.. But i can't.. so, i have tried my level best in explaining figuratively
Hope i have helped you.. :)
2007-02-22 04:30:46 · answer #5 · answered by Anonymous · 0⤊ 0⤋
It could be wrong or right. Is the box hollow? or covered on both ends? or possibly covered only on one end? If it is hollow the answer is supposed to be 960, if it is covered on only one end, then it is supposed to be 1120. Finally, if the box is covered on both ends, the answer should be 1280, which is the book's answer.
2007-02-22 04:15:14 · answer #6 · answered by deniçà 2 · 0⤊ 0⤋