# Thread: Need help to calculate for height for a cylinder.

1. ## Need help to calculate for height for a cylinder.

Need help with home work.
What length of 71 cm in diameter(inside) pipe is required to make a water storage tank with a capacity of 94 litres?
What is the length in cm???
I am having trouble with this one.
Need help please, thanks.
Joanne

2. Originally Posted by bradycat Need help with home work.
What length of 71 cm in diameter(inside) pipe is required to make a water storage tank with a capacity of 94 litres?
What is the length in cm???
I am having trouble with this one.
Need help please, thanks.
Joanne
The capacity is $\displaystyle 94\,\textrm{L} = 94\,000\,\textrm{mL}$.

So the volume is $\displaystyle 94\,000\,\textrm{cm}^3$.

You should know that the volume of a cylinder is given by the formula:

$\displaystyle V = \pi r^2 h$.

Since the diameter is $\displaystyle 71\,\textrm{cm}$ the radius is $\displaystyle 35.5\,\textrm{cm}$.

So $\displaystyle 94\,000\,\textrm{cm}^3 = \pi \left(35.5\,\textrm{cm}\right)^2 h$.

Solve for $\displaystyle h$.

3. Originally Posted by Prove It The capacity is $\displaystyle 94\,\textrm{L} = 94\,000\,\textrm{mL}$.

So the volume is $\displaystyle 94\,000\,\textrm{cm}^3$.

You should know that the volume of a cylinder is given by the formula:

$\displaystyle V = \pi r^2 h$.

Since the diameter is $\displaystyle 71\,\textrm{cm}$ the radius is $\displaystyle 35.5\,\textrm{cm}$.

So $\displaystyle 94\,000\,\textrm{cm}^3 = \pi \left(35.5\,\textrm{cm}\right)^2 h$.

Solve for $\displaystyle h$.
THANK YOU for your help on this. I understand. I forgot you had to convert and only got half way and did not know what to do, but I do now. Appreciate it,
J

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