Let the speed of boat and stream be v and u respectively. Given, upstream speed of boat = 18 km/h v - u = 18 ...(i) According to question, 18 = u + u of 500% 18=u+u×
500
100
⇒ 6u = 18 ⇒ u = 3 km/h From Eq. (i), v - 3 = 18 v = 21 km/h Hence, distance covered by the boat whiletravelling in downstream = Speed x Time =(v+u)×3 =(21+3)×3=24×3 = 72 km