00:01
Alright then so here's what we have as an alloy copper and gold for simplicity we denote letter a for gold and letter b for copper what we know from the question is mass of a plus mass of b is 7 grams and volume of a plus volume of b plus volume of b equals 479 cubic centimeters so we do know this is equation one and equation two further we know from the density relationships that one cubic centimeter of gold or a weighs 19 .3 grams so we have volume in question of a and we got mass in question of a then we have this relationship mass of a always equals 19 .3 times volume of a in any relationship.
01:17
Similarly, so we don't know this, equation three, for copper, one cubic centimeter of copper weighs 8, 96 grams.
01:31
So volume in question of copper equals mass in question of copper.
01:36
So mass of copper always, eight, nine, six times volume of copper.
01:42
And this is equation 4.
01:45
What we do now, or we could do, is 3 and 4 could be replaced in equation 1.
01:53
And therefore, we get 19 .3 times volume of a plus 896 times volume of b equals 7.
02:09
We still have volume of a equals 479, 0 .4 .479 minus volume.
02:20
Of b from equation 2.
02:22
So we replace the latter into the first into the former and that's what we get after simplification.
02:34
Okay, so we multiplied 19 .3 volume a and we replace volume a with this second value and then after simplification we got this so we can calculate volume b as 0 .217 cubic centimeters...