A man rows to a place 48km distant and back in 14 hours. He finds
that he can row 4km with the stream in the same time as 3km against the
stream. The rate of the stream is
1.1 km/hr
1.2 km/hr
2.2km/hr
1.7 km/hr
Explanation:
Suppose he moves 4km downstream in x hours
Then, downstream a= 4 / x km/hr
Speed upstream b = 3/ x km/hr
48 / 4 /x + 48 / 3/x = 14
x/4 + x/3 = 14/48 = ¼
3x + 4x / 12 = ¼ è 7x x 4 = 12 è x = 3/7
a=28/3 km/hr b = 7km/hr
rate of stream = ½ (28/3 – 7 )
= 7/6 = 1.1 km/hr
Suppose he moves 4km downstream in x hours
Then, downstream a= 4 / x km/hr
Speed upstream b = 3/ x km/hr
48 / 4 /x + 48 / 3/x = 14
x/4 + x/3 = 14/48 = ¼
3x + 4x / 12 = ¼ è 7x x 4 = 12 è x = 3/7
a=28/3 km/hr b = 7km/hr
rate of stream = ½ (28/3 – 7 )
= 7/6 = 1.1 km/hr