In my Physics lab, we were asked to measure a table's dimensions (L, W, T) in cm and repeat this measurement 5 times. Then we were asked to compute the average of our measurements, the error of each, then to find the average of our error. I have no problem with the lab, just a question on what to do with sig figs. For example, if I calculate the Length to be 19+5/16, My measuring tape can measure to the nearest 1/16", then how many sig figs would I use after converting it to cm? This is what I get...

19+5/16 in = 304/16 +5/16 in = 19.3125 in

Okay, so far, do I need to use sig figs, or do I leave it alone where I just converted a fraction to a decimal, not changing its units?

Continuing, I convert 19.3125 into cm by multiplying by 2.54 cm, and I get 49.05375 cm (Unrounded to sig figs)

At this point, I round to 49.0538 cm, I assume bc I converted between units.

This doubles down and confuses me when I repeat the measurement and get 19+4/16 in

This time when repeating the process, I get 19.25 in....... 4 sig figs, so I convert to cm and get 48.895 cm (Unrounded)

But if I round this answer, I get 48.90

How can both answers measured at the nearest 1/16in have different sig fig amounts?

Answer rating: 100% (QA)

The number of significant figures in a length measurement is determined by the smallest graduation o... View the full answer