ritula wrote:A swimmer practiced in a still water inlet a river made in its bank, and achieved a speed of 4 km/h. When she was swimming upstream in the river, however, she could only make 3 km/h. One day the swimmer swam into the river from the inlet, then doubled the covered distance going downstream, and finally came back. She averaged 3.8 km/h that day. What was her downstream speed?

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IMO 5

Speed in still water = 4 km/h

Let x be the speed of the stream

Speed while swimming upstream = 4-x = 3

Speed while swimming downstream = 4+x = 5

OA?

I dont understand how other information can be useful.

Let distance = 60

60/4 = 15 still water
60/3 = 20 upstream
120/5 = 24 downstream


total distance = 60+60+120 = 240
total time = 15+24+20 = 59

Avg. speed = 240/59 = 4~3.8

Let me know if you guys think otherwise.

Whats the OA?

I am getting 11.4/2.2

I am getting speed=6.
What is OA

Ans is 5