Question 1203028
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Actually, it is very naïve approach to think that volume of an alloy is the sum of volumes of composites.


It is well known fact for all metallurgists just more than several hundreds years 
that due to shrinking effect, the volume of an alloy, as a rule, is not equal to the sum 
of volumes of composite metals.


I know and remember it from learning Science in my middle school years 
(which means that this phenomenon is of the commonly known level of knowledge).



For further information and to develop your knowledge, look, read and learn from these sources


https://www.diva-portal.org/smash/get/diva2:218833/FULLTEXT01.pdf


https://nvlpubs.nist.gov/nistpubs/jres/8/jresv8n1p37_A2b.pdf   

    (publication of the 1932 year).


Having enough free time, anyone can find hundred of articles, tens textbooks, monographs 
and handbooks in metallurgy and material science that teach this phenomenon, which is important
and essential for alloys.



        Therefore, a competent Math problems composer will NEVER 
        propose such a problem, as in this post, to school students.


            Masses can be added for alloys, but volumes not.



Adding volumes of alloys to find the volume of the final product is the sign of a general 
incompetence in the subject.


If in this problem the numbers / (the quantities) be the masses in consistent units,
it would be a normal / (correct) problem with the solution as in the post by another tutor.


But with the given interpretation, when the given quantities are the VOLUMES,
the problem is like a lame horse and does not suit for proper teaching of students.



The cause WHY the volume of the resulting alloy is not the sum of volumes 
of participating components is that crystal structure of the resulting alloy 
is DIFFERENT from that of the components.



The phenomenon I am talking about, is close (although is not identical) 
to the fact that the volume of ice is greater than the volume of water.


It is why icebergs float on the surface of water . . .