Question

A man swimming downstream overcome a float at a point

M. After travelling distance D, he turned back and passed

the float at a distance of D

2

from the point M, then the

ratio of speed of swimmer with respect to still water to

the speed of the river will be​

Answer 1

Answer:

3:1

Explanation:

Let say Speed of Swimmer in Still water =  A  m/s

& Speed of Stream = B m/s

Speed of streamer downstream = A+B m/s

Distance covered = D

Time Taken = D/(A+B)

Distance  covered  by Float in same time =  B D/(A+B)

Upstream speed by swimmer = A - B  m/s

Distance covered = D/2

Time Taken = D/2(A-B)

Distance  covered  by Float in same time = BD/2(A-B)

B D/(A+B) + BD/2(A-B)  = D/2

=> 2B/(A+B)  + B/(A-B) = 1

=> B (2A - 2B + A + B) = (A+B)(A-B)

=> B(3A - B) = A² - B²

=> 3AB - B² = A² - B²

=> 3AB = A²

=> 3B = A

=> A/B = 3/1

=> A:B = 3:1

ratio of speed of swimmer with respect to still water to the speed of the river will be​ 3 : 1

Answer 2

Answer:

Explanation:

Answer = 3:1

All the explaination are given in the photos below

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