Question

the speed of the current is 4 kmph. A boat travels 6km upstream and retirns back to the starting point in 2 hours . whta si the speed of boat in still water??
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Answer 1

Answer:

Let the speed of the boat in still water be x

6/(x+4) + 6/(x-4) = 2

6{x -4 + x +4}/((x+4)(x-4)) = 2

6×2×x = 2(x+4)(x-4)

6x = (x+4)(x-4)

x^2 - 6x -16 =0

x^2 - 8x + 2x - 16 = 0

(x -8)(x + 2) =0

x -8=0, x =8 Ans

x + 2 =0 gives x = -2 which is not possible.