$4\mathrm{.}3($all$)$

Consider the following instruction mix:

$4\mathrm{.}3\mathrm{.}1$ What fraction of all instructions use data memory?

$4\mathrm{.}3\mathrm{.}2$ What fraction of all instructions use instruction memory?

$4\mathrm{.}3\mathrm{.}3$ What fraction of all instructions use the sign extend?

$4\mathrm{.}3\mathrm{.}4$ What is the sign extend doing during cycles in which its output is not needed?