Answer
a) $256.0$
b) $4.893\times10^{-4}$
c) $2.901\times10^{-4}$
d) $2231\times10^{3}$
Work Step by Step
a) $255.98612$ rounds to $256.0$ if it is rounded to 4 significant figures because rounding the decimal '.98612' simply rounds to the next closest whole number 256 but since the question asks for 4 significant figures, it would be 256.0.
b) $4.893\times10^{-4}$ is rounded to 4 significant figures and then put into scientific notation.
c) $2.900856\times10^{-4}$ rounds to $2.901\times10^{-4}$ because looking at the fourth digit of 0 and the preceding digit 8, the 0 would round up to 1.
d) $2231479$ rounds to $2231\times10^{3}$ because the last digts are smaller than 500 (i.e 479) and therefore, we round down and put into scientific notation.
