Question

if the earth dug out from a well which is 20m deep and has a diameter 7m,is spread over a rectangular plot of area 308 sq.m then find height of the platform formed?

Answer 1

Hi there !

Here's your answer

Volume of earth dug = volume of cylindrical well

diameter = 7m
radius = 7/2 m

$volume \: = \pi {r}^{2} h$

$= \frac{22}{7} \times \frac{7}{2} \times \frac{7}{2} \times 20m$

$= 770 {m}^{3}$

Area of rectangular plot = 308m²
this is length × breadth or what we call is the base area

Volume of earth = volume of the Earth to be spread on top which will obviously rise in level

let the rise in level or the height be 'h'

$volume \: = l \times b \times h$
lb = 308 m²

$770 = 308 \times h$
$\frac{770}{308} = h$
$h = 2.5$

so, the height is 2.5 m

or

250cm