Multiple choice

Two ports A and B are 90 km apart from each other. Ship 1 started from port A and ship 2 started from port B at the same time. If both of them proceed in the same direction, they will meet in 9 hours and if they proceed in opposite directions, they will meet in 9/7 hours. Calculate their respective speeds in km/hr. (Suppose speed of ship 1 is more than ship 2)

  1. 10 km/hr and 30 km/hr

  2. 40 km/hr and 30 km/hr

  3. 40 km/hr and 10 km/hr

  4. 90 km/hr and 70 km/hr

  5. 10 km/hr and 90 km/hr
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let v1, v2 be speeds. Same direction: (v1-v2) = 90/9 = 10. Opposite direction: (v1+v2) = 90/(9/7) = 70. Adding equations: 2v1 = 80 => v1 = 40. v2 = 30.

AI explanation

Let the speed of ship 1 be x km/hr and the speed of ship 2 be y km/hr. When moving in opposite directions, their relative speed is (x + y) = 90 divided by (9/7), which results in 70 km/hr. When moving in the same direction, their relative speed is (x - y) = 90 divided by 9, which results in 10 km/hr. Solving the equations x + y = 70 and x - y = 10 yields x = 40 and y = 30, so the respective speeds are 40 km/hr and 30 km/hr.

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