Question

a boat covers a distance downstream in 8 hours and come back upstreams in 10 hours. if the speed of the boat current be 1 kmph , the distance in km of the one way journey is​

Answer 1

Answer:

$let \: the \: speed \: of \: river \: be \: v \: and \: distance \: \\ covered \: be \: d \: km.$

$for \: upstream \: \\ 10 = \frac{d}{v - 1} \: \: \: \: \: ... \: eq \: 1 \\ \\ for \: downstream \\ 8 = \frac{d}{v + 1} \: \: \: \: \: \: ... \: eq \: 2 \\ \\ dividing \: 1 \: and \: 2 \: we \: get \: \\ \frac{4}{5} = \frac{v - 1}{v + 1} \\ \\ 4v + 4 = 5v - 5 \\ \\ v \: = 9m {s}^{ - 1} \\ \\ putting \: in \: eq \: 1 \\ \\ 10 = \frac{d}{8} \\ \\ \underline{d = 80km}$

$\mathscr{\large{Thanks}}\heartsuit$