Mass and volume the same??

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HeyArnold: Senior | Next Rank: 100 Posts; Posts: 31; Joined: Sun Jul 31, 2011 10:55 am; Followed by:1 members

Mass and volume the same??

by HeyArnold » Sat Oct 22, 2011 12:18 pm

The mass of 1 cubic meter of a substance is 800 kg under certain conditions. What is the volume in cubic centimeters of 1 gram of this substance under these conditions?
1 kg =1000 g and 1 cubic meter = 1 000 000 cubic cm

In this problem, if you were to make the assumption that mass and volume are the same thing you'd get it correct, if not, you'd spin (like I did).

Mass and volume although related are not the same thing, density has an impact (Mass / Density = Volume). I know this is irrelevant, but has anyone noticed similar "synonyms" that GMAT uses so I can be more prepared?

Thanks!

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Source: Beat The GMAT — Problem Solving | Sat Oct 22, 2011 12:18 pm

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Anurag@Gurome: GMAT Instructor; Posts: 3835; Joined: Fri Apr 02, 2010 10:00 pm; Location: Milpitas, CA; Thanked: 1854 times; Followed by:523 members; GMAT Score:770

by Anurag@Gurome » Sat Oct 22, 2011 12:27 pm

HeyArnold wrote:The mass of 1 cubic meter of a substance is 800 kg under certain conditions. What is the volume in cubic centimeters of 1 gram of this substance under these conditions?
1 kg =1000 g and 1 cubic meter = 1 000 000 cubic cm

Volume of 800 kg substance = 1 cubic meter = 1,000,000 cubic cm
Volume of 1 kg, i.e. 1000 g substance = (1,000,000/800) cubic cm
Volume of 1 g substance = (1,000/800) = 1.250 cubic cm

HeyArnold wrote:In this problem, if you were to make the assumption that mass and volume are the same thing you'd get it correct, if not, you'd spin (like I did).

Mass and volume are totally different quantities. They are not same.
What makes you conclude they are same?

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HeyArnold: Senior | Next Rank: 100 Posts; Posts: 31; Joined: Sun Jul 31, 2011 10:55 am; Followed by:1 members

by HeyArnold » Sat Oct 22, 2011 12:30 pm

Thanks Anurag,

What confused me is that the problem states "the mass of 1 cubic mter is 800 kg"

You then go on to say that the mass of 800 kg is = 1,000,000 cubic cm and so on...

In my mind, I thought I needed to somehow first convert the mass of 1 cub meter into volume and then compare.

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GMAT/MBA Expert

Anurag@Gurome: GMAT Instructor; Posts: 3835; Joined: Fri Apr 02, 2010 10:00 pm; Location: Milpitas, CA; Thanked: 1854 times; Followed by:523 members; GMAT Score:770

by Anurag@Gurome » Sat Oct 22, 2011 12:44 pm

HeyArnold wrote:Thanks Anurag,

What confused me is that the problem states "the mass of 1 cubic mter is 800 kg"

You then go on to say that the mass of 800 kg is = 1,000,000 cubic cm and so on...

In my mind, I thought I needed to somehow first convert the mass of 1 cub meter into volume and then compare.

The phrase "the mass of 1 cubic meter is 800 kg" has no problem at all. This means the volume of 800 kg of the substance is 1 cubic meter. To be more precise, 1 cubic meter is the volume of the substance and 8 kg is the mass.

I never said "the mass of 800 kg is...".
That would be wrong as 800 kg is the mass. Hence, "mass of 800 kg..." won't make any sense.