Velocity of swimmer across river = 1.30 m/s
Distance arrived downstream = 48 m
Width of river = 64 m
Time taken to cross river = [tex]\frac{Width of river}{Velocity across river}[/tex]
= [tex]\frac{64}{1.30} =49.23 s[/tex]
Speed of river current = [tex]\frac{Distance arrived downstream}{Time taken to cross river}[/tex]
= [tex]\frac{48}{49.23} = 0.975 m/s[/tex]
So, the river is flowing at a speed 0.975 m/s.