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**austin81****Member**- Registered: 2005-03-21
- Posts: 39

A cylindrical tunnel 5.5m in diameter is driven through a mountain for a distance of 7km. the ezcavated earth i s spread to a depth of 50cm on the surface of a road 11m wide. Calculate the number of ilometers of the road that can be covered with all of the excavated earth. (Take pi as 22/7)

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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,608

These are nice problems ...

I think this one can be solved by just working out the volumes. Figure the volume of the cylinder, then divide it by (0.5 x 11).

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

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**austin81****Member**- Registered: 2005-03-21
- Posts: 39

thanks for that quotation and more espcially for the help

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**mathsyperson****Guest**

Total excavated earth: Pi*5.5m squared*7km=665500 cubic metres (Taking Pi as 22/7)

Length of road covered: 665500/(0.5m*11m)=121km.

Answer: 121km

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