Question

How many cubic meters of earth must be dug out to sink a well which is 20 m deep and has a diameter of 7 metres? If the earth so dug out is spread over a rectangular plot 28 m by 11 m, what is the height of the platform so formed?

Answer 1

Answer:

2.5m

Step-by-step explanation:

r=7/2m=3.5m

h=20m

volume of earth dug out =volume of well

                                          = $\pi r^{2}h$

                                          =22/7×3.5×3.5×20

                                          =770m³

L=28M

B=11M

H=?

volume of rectangular plot= volume of earth dug out

L×B×H=770m³

28×11×H=770

H=770/308

H=2.5m

Answer 2

Answer:

2.499≅2.5

Step-by-step explanation:

We first get the volume of the soil dug out by getting the volume of the hole dug.

Volume=3.142×3.5^2×20=769.79

769.79m3

The area of the field is=28×11=308m2

The soil level =769.79/308=2.499m

2.499m ≈2.5