Biology Maths question mark scheme dumb? Maths people unite

So just doing this question and my calculator gave an answer that was not on the mark scheme so I would be awarded 0 marks even though I did the exact calculations that were listed on the mark scheme but my calculator was 0.02 off the answer and there was no rounding needed to be done?Are my calculator settings wrong has the mighty casio scientific calculator failed me?


Here is the question without the biology jargon.

Calculate the percentage increase between 2.20 and 14.70.

I did
14.70-2.20=12.5
12.5/2.20=5.861
5.861*100=568.18

Mark scheme
award both marks for correct answer evidence=568.2 / 568 / 570;;

gains one calculation mark 12.5/2.2 × 100; = 568.2 / 568 / 570;;

You took it to 5 sig figs. Very bad thing to do.

The question used numbers which tool it to 3 sig fig, which would actually give u 568.2.

So just doing this question and my calculator gave an answer that was not on the mark scheme so I would be awarded 0 marks even though I did the exact calculations that were listed on the mark scheme but my calculator was 0.02 off the answer and there was no rounding needed to be done?Are my calculator settings wrong has the mighty casio scientific calculator failed me?


Here is the question without the biology jargon.

Calculate the percentage increase between 2.20 and 14.70.

I did
14.70-2.20=12.5
12.5/2.20=5.861
5.861*100=568.18

Mark scheme
award both marks for correct answer evidence=568.2 / 568 / 570;;

gains one calculation mark 12.5/2.2 × 100; = 568.2 / 568 / 570;;

The problem is that you're taking it to too many significant figures - your calculator is giving you the right result from those numbers. If you're given 2.20 as part of your data, that actually means $2.20\pm0.005$. You don't know what the next decimal place is, and you can't just assume it's 0.

The general rule is that your answer should have a maximum of one more significant figure than the piece of data with the smallest number of sig figs. In your case the 2.20 is only 3 sig figs, so you can't be confident about more than 4 figures, and realistically should probably be only quoting 2.