(b) Let the speed of faster swimmer be x km/h. Then, speed of slower swimmer = 10075​×x=43​x km/h Now, distance covered by both in 2 h. Faster swimmer = 2x km and slower swimmer = 43​x×2=23​x km After, 2 h the distance between them is 100 km.
From the figure, (OE)2+(OS)2=(ES)2⇒ (23​x)2+(2x)2=(100)2[Here, S = South direction, E = East direction, O = Origin] ⇒ 49​x2+4x2=10000⇒ 49x2+16x2​=10000⇒ 425x2​=10000⇒ x2=2510000×4​∴ x = 2510000×4​​ = 5100×2​ = 40 km/h ∴ Speed of faster swimmer = 40 km/h Direction of faster swimmer can also be taken towards East.