Practicing Success
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? |
4\(\frac{1}{2}\) 6\(\frac{3}{4}\) 4\(\frac{3}{4}\) 5\(\frac{1}{4}\) |
5\(\frac{1}{4}\) |
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 |