PET scanning often uses labeled with the isotope F-18.

the answer would be c

3 1/4 %

explanation:

in the analysis of systems that involve fluid flow, we frequently encounter the combination of properties u and pv.

answer;

18.5 seconds

explanation;

velocity is distance covered per unit time; it is given by displacement divided by time.

thus; time = displacement/velocity

total time = total displacement/velocity

total distance = 5000 meters south

total time = 5000/4.5

                  = 1111.11 seconds

but; 1 minute = 60 sec

thus; 1111.11 /60

                = 18.51 seconds

thus; the time taken is 18.5 seconds