A man can row 45 km downstream and return in a total of 9 hours. If the speed of the boat in still water is 2\(\frac{1}{3}\) times the speed of the current, then the speed of the current is?
Answer & explanation
Correct answer: option 4
Boat : Current
Speed → 7R : 3R
ATQ, \(\frac{45}{7R+3R}\) + \(\frac{45}{7R - 3R}\) = 9 hours
\(\frac{45}{10R}\) + \(\frac{45}{4R}\) = 9
\(\frac{315R}{20R^2}\) = 9
R = 1.75
Speed of the current = 3R = 3 x 1.75 = 5\(\frac{1}{4}\) km/hr