Aptitude - Volume and Surface Area - Discussion

v.ocyclinder= πr^2h.

Where π equals to 22/7.
22/7*1/20*1/20*h = 66,
11h/1400 = 66,
h = 92400/11,
h = 8400cm,
h = 8400/100m,
h = 84m.

Length of wire should be whole perimeter of cyclinder, why it is calculated same as height?

Please tell why the shape of wire is consider as a cylinder?

Why do they take 22/2 * 1/20 * 1/20? Please explain it.

They have given d diameter. But we need radius. So when 1 mm is divided by 2, we get 1/2 mm and to convert mm into cm we have to multiply it by 10.

Therefore, 1/2 multiply by 10, we get 1/20.

What is meant by 66 cubics? and why is it equal to the volume of a cylinder?

1/2 * 10 = 5 >_<.

But.

1/2 = .5 mm.

And to convert it into cm we have to divide it by 10.

So, .5/10 = .05cm.

5/100 = 1/20 cm.

@Suhani.

Yes. I too have same doubt.

Can anyone explain us please?

1 cubic centimeter equal to 1 millilitre volume of liquid, in this question silver metal liquid is used to make a wire, the wire is in the shape of cylinder , so we have to form silver wire, then 66 cubic centimeter silver metal liquid is changed to volume of the wire (Wire is in the form of cylinder, assume long thin wire. The length of the wire is also the height of the cylinder) then by using formula of the volume of the cylinder we can find the length of the wire, the formula is:
V = πr^2h.
Radius = diameter/2 = 1/2 mm
i.e To convert mm to cm use the following formula:
1 mm = 0.1 cm.
So, to convert 0.5 mm to cm, multiply 0.1 by 0.5.
i.e. 0.5 mm = 0.1 * 0.5 cm = 0.05 cm or 1/20 cm.
Then according to formula,
66 cubic cm silver metal liquid is equal to the volume of the wire.
Then, 22/7 * 1/20 * 1/20 * h = 66.

h = 66 * 20 * 20 * 7/22,
= 8400 cm,
= 84 m.

1/2 mm is (1/2)*10^-3 or (1/2)* 1/1000 or (1/20)* (1/100) or (1/20)*10^-2 .

10^-2 metre is nothing but centimetre