Math Is Fun Forum

austin81

Member

Registered: 2005-03-21

Posts: 39

yet another problem

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)

MathsIsFun

Administrator

Registered: 2005-01-21

Posts: 7,713

Re: yet another problem

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).

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

austin81

Member

Registered: 2005-03-21

Posts: 39

Re: yet another problem

thanks for that quotation and more espcially for the help

mathsyperson

Guest

Re: yet another problem

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