A boat takes total 8 hrs. to cover a distance of 64 km in upstream and 80 km in downstream. While it takes 8.5 hrs. to cover a distance of 80 km in upstream and 70 km in downstream. Find speed of the boat.
Answer & explanation
Correct answer: option 4
\(\frac{64}{x - y}\) + \(\frac{80}{x + y}\) = 8 ---(i)
\(\frac{8}{x - y}\) + \(\frac{10}{x + y}\) = 1 ---(i)
\(\frac{80}{x - y}\) + \(\frac{70}{x + y}\) = 8.5 ---(ii)
(i) x 10 - (ii) x 1
\(\frac{30}{x + y}\) = 1.5
x + y = 20
x - y = 16
x = 18, y = 2