Assume that a program requires the execution of $125$x$106$ FP $($floating point$)$ instructions, $130$x$106$ INT $($integer$)$ instructions, $150$x$106$ L$/$S $($load$/$store$)$ instructions, and $110$x$106$ branching instructions. These instructions have CPIs of $1,1,8$ and $4,$ respectively. Assume that the processor has a $5$ GHz clock rate.

a$.$ Is it possible to run the program twice as fast if we improve the CPI of just the L$/$S instructions? If so$,$ by how much? Show your calculations.

b$.$ What is the Speedup in the execution time of the entire program if the CPI of INT and FP instructions is reduced by $40\%$ and that of L$/$S and branching instructions is reduced by $50\%?$