It should be rounded to 2 significant figures since you cannot go to 1 significant figure if there is more than 1 So 2.8 has 2 significant figures so 11.8 should be rounded to 12
Considering the data you've given, if you want the result in cm, the numbers should be rounded to 9 and 3, thus giving a total of 12, with two significant numbers.
But taking into account the precision you've reported, looks like the decimals do matter, and in that case, the numbers should be rounded to 9.0 and 2.8, giving a total of 11.8, thus, three significative figures.
in the "score" section all you do is add all them up. And because there is a negative for ALL the numbers, all you do is add a negative after you add all the SCORES
