A coin contains 999 grams of nickel and 161616 grams of copper, for a total weight of 252525 grams. What percentage of the metal in the coin is copper?

Answer 1

this is a trick question, or it got copied incorrectly

999+ 161616 does not add to 252525

999+161616 = 162615

252525-161616 = 90909 not 999

without calculating it, you might notice 3^2 + 4^2 = 5^2 or 9+16=25

this looks suspiciously like a 3-4-5 right triangle or 9-16-25 right triangle, inflated by a factor of 111.

but not quite, as 111 x 9 = 999, but 111 x 16= 1776, (a patriotic number) and 111 x 25 = 2775

so that may be a misleading observation or it may indicate what went wrong when creating this problem.

If there were some 3rd component making each of the 3 add to 252525

then just plug the numbers into a calculator

161616 divided by 252525 =0.64 = 64%

= 64/100 = 32/50 = 16/25 which looks a lot like 161616/252525

which also = 1616/2525 = 16161616/25252525

= as many 16's in a row in the numerator divided by as many 25's in the denominator