Aptitude - Volume and Surface Area - Discussion

I can't understand this.

1mm=1/1000m, so 1/2000m.

And 1m=100cm, so 1/2000m=1/20cm.

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

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.

@Suhani.

Yes. I too have same doubt.

Can anyone explain us please?

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

1/2 is divided by 10.

1/2/10 = 1/2/10 (1/2/10/1 same thing).

Then.

1/2 * 1/10 = 1/20.

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.

We know that d = 2r then r = d/2mm and here d is given 1mm and 1mm convert in cm then r = 1/20cm.

@Rashmi, @Megha.

1cm=10mm.
? =1/2mm.
Cross multiplication

1/2 * 1/10.
= 1/2 * 10.
= 1/20 m.