Express the product and the quotients of the following to the correct number of significant figures:

$8\mathrm{.}45\frac{{10}^7}{6\mathrm{.}74}{10}^3=$

$9\mathrm{.}7\frac{{10}^8}{8\mathrm{.}6}{10}^{-2}=$

$4\mathrm{.}7\frac{{10}^{-2}}{5\mathrm{.}7}{10}^{-6}=$