$4\mathrm{.}17$ What is the composition, in atom percent, of an $o+$ alloy that contains $99\mathrm{.}7l{b}_m$ copper, $102l{b}_m$ zinc, and $2\mathrm{.}1l{b}_m$ lead?

$4\mathrm{.}18$ Convert the atom percent composition in $o+$ Problem $4\mathrm{.}17$ to weight percent.