A boat covers 40 km downstream in 4 hours and the same distance upstream in 8 hours. Find the speed of the stream. MCQ with Answer and Explanation

Explanation:
Perimeter of the track = 4 * 60 = 240 meters. Speed = 12 km/h = 12 * (5/18) = 10/3 m/s. Time required = Distance / Speed = 240 / (10/3) = 240 * 3 / 10 = 72 seconds.

Explanation:
Distance covered in 1 revolution = Total Distance / Number of Revolutions = 44000 meters / 2000 = 22 meters. Circumference = 2 * (22/7) * r = 22 => 44r / 7 = 22 => r = 154 / 44 = 3.5 meters.

Explanation:
Let original speed be s. 450/s - 450/(s+5) = 1 => 450(s + 5 - s) = s(s + 5) => 2250 = s(s + 5). Solving s^2 + 5s - 2250 = 0 gives (s - 45)(s + 50) = 0. Since speed is positive, s = 45 km/h.