Question

30. A man can row upstream 11km/hr and
downstream at 16 km/hr. Find man's rate in
still water.
(a) 13.5 km/hr
(b) 15 km/hr
(c) 17.5 km/h
(d) 10 km/hr​

Answer 1

Step-by-step explanation:

If the speed of a boat in still water is x km/hr and the speed of the stream is y km/hr, then:

Relative speed downstream = (x + y) km/hr.

Relative speed upstream = (x - y) km/hr.

x + y = 16-----(1)

x - y = 11-----(2)

________

2x= 27

=> x= 27/2 = 13.5 km/hr

Note for aptitude exams:

If upstream speed is x km/ hr and downstream speed is y km/hr,

then,

Speed of boat in still water = (x + y)/2 km/hr

Speed of stream = (x - y)/2 km/hr

Answer 2

Answer:

ANSWER IS (A) 13.5 km/hr