Problem $3$

Effective Miss Rate $=(0\mathrm{.}500\mathrm{.}04)+(0\mathrm{.}500\mathrm{.}08)=0\mathrm{.}02+00\mathrm{.}04=0\mathrm{.}06$ or $6\%$

$L1=0\mathrm{.}8ns+(0\mathrm{.}06100ns)=0\mathrm{.}8ns+6ns=6\mathrm{.}8ns$

AMAT $=0\mathrm{.}8ns+(0\mathrm{.}06(3ns+(0\mathrm{.}25100ns)))=0\mathrm{.}8ns+(0\mathrm{.}06(3ns+25ns))=$

$8ns+(0\mathrm{.}0628ms)=0\mathrm{.}8ns+1\mathrm{.}68ns=248ns$

Final Answer:

qqqq AMAT with only L$1$ cache: $6.8$ns

AMAT with L$1$ and L$2$ caches: $2\mathrm{.}48$ ns