Since the thread has come to an end, I thought I could pose some thoughts without hijacking.
Sometimes I think too much!
When I did this problem my result was
1.9714285714285714285714285714286
(well, that is as far as my calculator went).
Now the only value we had as a given not including the percents was 4.6 grams.
So I assumed that my value needed to be rounded.
What I am not sure of is what the current Pedagogy or practice suggests as the level of rounding.
Is it 2.0 or 1.97 or 1.971 or 1.9714.
The triple beam balance I use goes to 0.1 grams.
I could only measure 2.0 grams as the closest value.
That level of rounding would match the original base number as 4.6.
I also use a digital scale that goes to 0.01 grams.
I could then measure 1.97 grams.
But would the original base number have been noted as 4.60?
And lastly I know there are scales that measure to 0.0001 grams.
So I could measure 1.9714 grams.
But then would the original base number be 4.6000?
My friend just called me pedantic for even thinking about this problem.
I know I knew the answer to this at sometime but can not articulate it - so I mention it here.