Multiple choice

Two cars pass each other in opposite direction. How long would they take to be 500 km apart? I. The sum of their speeds is 135 km/hr. II. The difference of their speed is 25 km/hr.

  1. I alone sufficient while II alone not sufficient to answer

  2. II alone sufficient while I alone not sufficient to answer

  3. Either I or II alone sufficient to answer

  4. Both I and II are not sufficient to answer

  5. Both I and II are necessary to answer
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Relative speed = speed1 + speed2. Distance = 500 km. Time = Distance / Relative Speed. Statement I gives the sum of speeds directly, so time = 500 / 135. Statement II gives the difference, which is not enough to find the sum.

AI explanation

When two objects move in opposite directions, their relative speed is the sum of their individual speeds. Statement I provides this sum directly as 135 km/hr, so the time to be 500 km apart is 500 divided by 135. Statement II only gives the difference of their speeds and cannot yield the relative speed, making statement I alone sufficient.

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