Question

A well is dug 20m deep and it has a diameter 7m . The earth which is so dug out is spread evenly on a rectangle plot 22m long and 14m broad .What is the height of platform formed?​

Answer 1

As per the question,

Volume of Earth dug out from well = Volume of platform

So, Volume of Cylinder = Volume of Cuboid

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

So,

$\frac{22}{7} \times \frac{7}{2} \times \frac{7}{2} \times 20 = 22 \times 14 \times h$

$h = \frac{22}{7} \times \frac{7}{2} \times \frac{7}{2} \times \frac{20}{22 \times 14}$

$h = \frac{5}{2} = 2.5m$

Therefore, h = 2.5 metres

Hope this helps

Answer 2

diameter =7m

radius =7/2 m

Volume of cylinder=

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

=22/7×7/2×7/2×20

=35×22

Volume of the rectangular plot =l×b×h

=Volume of the earth dug out

35×22=22×14×h(height of the platform)

h=35×22/22×14

h=5/2

Hence,height of the platform is 2.5 m