A cylindrical tank has an internal radius of 7 m and a height of 10 m. If the tank is 40% filled with water, what is the volume of the water in it? (Take \(\pi=\frac{22}{7}\))
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 616 m3
The volume of a cylinder is \(\pi r^2h\); the water fills 40% of this volume.
Volume of the tank \(\displaystyle =\frac{22}{7}\times7\times7\times10=1540\) m3
Water \(\displaystyle =\frac{40}{100}\times1540=616\) m3
Why the other options are incorrect
Option (1) 1540 m3 — Incorrect. This is the volume of the full tank, not of 40% of it.
Option (2) 924 m3 — Incorrect. This is 60% of the tank, the empty part, not the water.
Option (3) 780 m3 — Incorrect. 780 m3 is about 51% of the 1540 m3 tank, not 40%; 40% of 1540 m3 is 616 m3.