Question

A cylinder shaped water tank has a radius of 5 m and a height of 10 m.

Answer 1

Data:
v (volume) = ?
h (height) = 10 m
r (radius) = 5 m
Adopting: $\pi \approx 3.14$

Formula:
$V = h* \pi *r^2$

Solving:
$V = h* \pi *r^2$
$V = 10*3.14*5^2$
$V = 10*3.14*25$
$\boxed{V=785\:m^3}}\end{array}$

If:

785 m³ → 100%
y m³ → 75%

Solving: Rule of three (directly proportional)
$\frac{785}{y} = \frac{100}{75}$
multiply cross
$100*y = 785*75$
$100y = 58875$
$y = \frac{58875}{100}$
$\boxed{\boxed{y = 588.75\:m^3}}\end{array}}\qquad\quad\checkmark$

Answer:
The volume of water that the tank contains when it is 75% full is 588.75 m³