Steady speed of river = 0.480 m/s
Swimming speed of student in still water = 1.40 m/s
When the student is swimming upstream the velocity he is going up = 1.40-0.48= 0.92 m/s
When the student is swimming downstream the velocity he is going down = 1.40+0.48= 1.88 m/s
Time taken to travel upstream = [tex]\frac{1000}{0.92} =1087 seconds = 18.12 minutes[/tex]
Time taken to travel downstream = [tex]\frac{1000}{1.88} =592 seconds = 8.87 minutes[/tex]
Total time taken = 18.12+8.87 = 26.99 minutes
