Sorry, but I don't under stand what you are talking about.
The answer is three significant figures. The 1 and the 7 are both significant, because they are non-zero quantities.
This is where significant figures gets a little more complicated, because if a zero is used as a placeholder (i.e. 0.00027 cm) then it is insignificant.
But in the case above, the zero isn't being used as a placeholder, and thus, is significant.
The mean is 52 because 42+45+58+63=208 then you divide it by the amount of numbers: 4 : 208 divided by 4= 52
0<4x + 8<12 BADDA-BING-BADDA-BOOM!!! :-)
