Signficant figures of calculated values?

Question

Consider the above table. The AS practical examination markscheme states that the signficant figures of calculated values should be the same or one more than the values it was calculated from. We also use to the quantity with the lowest significant figures. My problem with this, is that in nuanced occasions, we have it such that all calculated data should be recorded to $2sf$. However, a single value, in this instance $0.9$ is recorded to 1sf despite all the others being to $2sf$. So would this be considered wrong?

https://gceguide.com/resources/notes/physics-9702/level-physics-practical-paper-3/

I used the link above, and it stated these rules are provided an example table, the one above. However, I don't think the $0.9$ value obeys with these cambridge AS rules. So should I record it to $2dp$?

Answer 1

If you have a scale calibrated in $0.1$ units then the readings will be in multiples of $0.1$ units unless interpolation is performed.
Looking at the table there is no evidence of interpolation being used.

If the value is $0.7$ then the range might be taken to be $0.65$ to $0.75$ which represents an error of $\pm 0.05/0.7\times 100\approx\pm 7\%$.
This is the percentage error in $1/0.7 = 1.428 . . .$ which corresponds to an error of $\pm 0.1$.

Thus using the value $1.4$ in the table seems reasonable?