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Question
The height of a rectangular solid is 5 times its width and its length is 8 times its height. If the volume of the wall is 102.4 cm3, find its length.
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Solution
Height of rectangular solid = 5 × width
and length = 8 × height = 8 × 5 × width = 40 × width
Volume = 102.4 cm3
Let width = w
Then height = 40w
and height = 5w
`therefore "w" xx 40"w" xx 5"w" = 102.4`
`"w"^3 = 102.4/(40 xx 5) = 0.512`
= `(0.8)^3`
∴ w = 0.8
∴ Length = 40w = `40 xx 0.8`
= 32 cm
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