Let the time taken by line to fill lake = t hours
Water streams 15 km in 60 minutes, in this way, it will stream 15t meters in t hours.
We realize that,
Volume of cuboidal lake up to tallness 21 cm = Volume of water that goes through pipe in “t” hours
Thinking about cuboidal lake,
Length, l = 50 m
Broadness, b = 44 m
Stature, h = 21 cm = 0.21 m
We realize that,
Volume of tank = lbh
Volume of water \[=\text{ }50\left( 44 \right)\left( 0.21 \right)\text{ }=\text{ }462\text{ }m3\]
Thinking about round and hollow line
Base width = 14 cm
Base span, r = 7 cm = 0.07 m
Stature, h = 15t km = 15000t m
We likewise realize that,
Volume of a chamber = πr2h
Volume of water passed in pipe
\[=\text{ }\pi \left( 0.07 \right)2\left( 15000t \right)\]
\[=22/7\text{ }\times \text{ }0.07\text{ }\times \text{ }0.07\text{ }\times \text{ }15000t\]
= 231t cm3
Thus, we have
231t = 462
t = 2 hours
Time needed to top tank off to a tallness of 25 cm is 2 hours.