Given a parallel runtime of 30s on 5 cores and a serial runt

Solution

Formula :

Speed up S(n) = Runtime on single CPU / Runtime time on N parallel processrs

or

Speed up S(n) = (serial runtime t_s)/(parallel t_p)

Runtime on single CPU (t_s) = 120s.

Runtime time on 5 cores (t_p) = 30s.

Substitute the corrosponding values on the above formula.

Speed up S(n) = 120 s / 30 s

Speed up S(n) = 4 .

Therefore the speed up is 4 times.