I found this exercise (see below) in one of my basic chemistry books at the end of the first chapter. It sounds correct to me.
"Twenty years ago an ancient artifact was determined to be 1900 years old. Today it is determined to be 1920 years old."
Where am I going wrong?! Twenty years ago it would have been 1987 so the artifact must date back to the year 87 a.D.
(I subtracted the 20 years from today's date, and I subtracted 1900 from 1987). So, then you add 87 a.D. to 1920 and you get back the current year. This is why it sound correct to me!
2007-10-13 02:31:46 · 5 answers · asked by sharon 3 in Science & Mathematics ➔ Mathematics
What's wrong with it is that it doesn't take into account the precision with which the original measurement was made. The original measurement of 1900 years has only two significant digits, and thus an implied error range of ±100 years. However, the second statement has three significant digits of accuracy, and thus an implied error range of only ±10 years. A computation of the age based on the fact that it was X years old Y years ago _cannot_ have more accuracy than the original measurement, so reporting a figure with greater accuracy than the original measurement is fallacious. It would be as if I dated some rock to be 2.8 billion years old, waited ten seconds, and then reported "the rock is now 2,800,000,000 years and ten seconds old" -- I didn't know it's age to within ten seconds of accuracy ten seconds ago, so I cannot possibly have that information now.
2007-10-13 03:27:11 · answer #1 · answered by Pascal 7 · 0⤊ 0⤋
Well when they found it was 1900 years old and twenty years later it was 1920 years old. It is said a little tricky. You shouldnt have to do any math to figure it out.
2007-10-13 09:44:34 · answer #2 · answered by meganvs1221 3 · 0⤊ 0⤋
I agree with you sharon i think it is correct. It has nothing to do with real dates so when the book was published doesn't matter. the question could have been asked ten years ago or fifty years into the future.
2007-10-13 10:38:34 · answer #3 · answered by Anonymous · 0⤊ 0⤋
I agree with ktm... it doesnt necessarily means that you just have to subtract dates, what if the book was published 3 years ago?!?
2007-10-13 09:52:57 · answer #4 · answered by criselda 3 · 0⤊ 0⤋
Are you considering when the book was published?
2007-10-13 09:38:47 · answer #5 · answered by ktm 3 · 0⤊ 0⤋