Length of circular track is:
L = 2*r*pi
He run 3/4 of it so length is:
L' = 3*2/4*r*pi = 3/2*r*pi
To calculate speed of his movement we use formula:
v = s/t where s = L' and t = 1 minute 45 seconds = 105 seconds
v = L'/t = 3*r*pi/2*105
v = r* pi/70
If we take that r = 1
answer
[tex] \pi /70[/tex]
