Question

A well of inner diameter 14 m is dug to a depth of 12 km. Earth taken out of it has been evenly spread all around it to a width of 7 m to form an embanknent. Find the height of the embankment so formed.

Answer 1

GIVEN width of embankment = 7mts
 its inner radius (r) = 7 ms and outer radius (R) = 7+7=14mts

volume of earth dug out = vol of soil in embankment
πr²h = vol of soil in embankment
22/7×7²×12000 = π h ( R²- r² )
1848000 = 22/7 × h × ( 14²-7² )
1848000 × 7/22 = h x 147
h = 84000 x 7 / 147
h = 588000 / 147
h = 4000 mts

Answer 2

hey
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•volume of well or earth dug out = πr^2h
diameter = 14m , radius =14/2=7m
depth / height = 15m
•now volume = 22/7×(7)^2×15
=105×22

•volume of embankment =π(R^2-r^2)×h
outer radius (R) = outer width + inner radius
= 7+7=14m
inner radius(r) = 7 m
height = ?
•volume = 22/7 ( 14^2-7^2)×h
=22/7×196-49×h
=22/7×147×h
=22×21×h

•earth taken out of well is spread over all around it forming a embankment

•volume of well = volume of embankment

105×22=21×22×h
105×22/21×22 = h
105×22/462=h
h=5m

hence height is 5 m

hope helped
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