#### Answer

a) $9.44\times10^{-3}$
b) $5.69\times10^3$
c) $1.19\times10^1$
d) $1.22\times 10^2$

#### Work Step by Step

a) Both number have three significant figures:
$1.52\times6.21=9.4392$; rounded to three significant figures: $9.44$
b) The first number's decimal needs to be shifted to the right once:
$(62.17-5.23)\times 10^2=56.94\times10^2$
Only two digits after the decimal are allowed in the scientific notation: $5.69\times10^3$
c) The number with fewer significant figures is the denominator with 3, so the answer must have 3 as well.
$1.19\times10^1$
d) Since this calculation only involves multiplication and division, we can look at which number has the fewest significant figures (0.0546 with 3) and report the answer with that number of significant figures.
$121.678=1.22\times 10^2$