Question

The volume of the cylinder is $400{mm}^3$. Its diameter is $20$ mm. Find the height (use $\pi =3.14$).

• A. $0.075$ mm
• B. $1.27$ mm
• C. $0.071$ mm
• D. $0.072$ mm

Answer 1

The correct option is B $1.27$ mm

Volume of cylinder is $V=\pi r^{2}h$

Here, the volume is $400$ mm${}^3$ and diameter is $20$ mm and therefore, the radius is half of diameter that is $r=10$ mm.

Thus,

$V=\pi r^{2}h\Rightarrow 400=\frac{22}{7}\times {\left(10\right)}^2\times h\Rightarrow 400=\frac{22}{7}\times 100\times h\Rightarrow 400\times 7=22\times 100\times h\Rightarrow 2800=2200\times h\Rightarrow h=\frac{2800}{2200}=1.27$

Hence, the height of the cylinder is $1.27$ mm.