Question

QUESTION 3 -A 20m
deep well with diameter 7m is dug and the
earth from digging is evenly spread out to
form a platform 22m by 14m.Find the height
of the platform.
​

Answer 1

Step-by-step explanation:

Diamter = 7 m

so, radius = 3.5 m

Earth dug out from (cylindrical) well

=π×r×r×h= 7

22 ×3.5×3.5×20

=770m3

to from platform ...... (cuboidal)

volume of cuboid = l×b×h

770=22×14×h

so, height = 22

770 ×14=2.5m

Answer 2

GIVEN:-

h1 = 20m

d = 7m

r = 3.5m

Length of platform = 22m

Breadth = 14m

━━━━━━━━━━━━━━━

Volume of platform = Volume of well

$\implies$$\small\sf{l \times b \times h1 = \pi {r}^{2}h2}$

$\implies$$\small\sf{22 \times 14 \times h1 = \frac{22}{7} \times 3.5 \times 3.5 \times 20}$

$\implies$$\small\sf{308 \times h1 = 22 \times 0.5 \times 3.5 \times 20}$

$\implies$$\small\sf{308 \times h1 = 770}$

$\implies$$\small\sf{h1=\frac{770}{308}}$

$\implies$$\small\sf{h1=2.5m}$