Multiple choice

Directions: The question given below is followed by two statements I and II. You have to determine whether the data given in the statement is sufficient for answering the question. You should use the data and your knowledge of Mathematics to choose the best possible answer. How many seconds will Train A, running at 90 km/h, take to completely cross a man going in the opposite direction on the platform? (I) Speed of the man is 7.2 km/h. (II) It takes 27 seconds for the train to completely cross the same man, if going in the same direction.

  1. The question can be answered by using statement I alone but cannot be answered using the other statement alone.

  2. The question can be answered by using statement II alone but cannot be answered using the other statement alone.

  3. The question can be answered by using either of the statements alone.

  4. The question can be answered using both of the statements together, but cannot be answered using either of the statements alone.

  5. The question cannot be answered even by using both the statements together.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

To find the time taken to cross the man, we need the relative speed and the length of the train. Statement I gives the man's speed, and Statement II provides the time taken when moving in the same direction, which allows us to calculate the train's length using the relative speed formula. Both statements are required to determine the length of the train and subsequently the time taken to cross the man in the opposite direction.

AI explanation

To find the crossing time, we need the sum of the train's and man's speeds, along with the train's length. Neither statement alone provides the train's length. Using statement II, we know the relative speed in the same direction is (90 - 7.2) km/h and the time is 27 seconds, which allows us to calculate the train's length. We then add the speeds from both statements to find the relative speed in opposite directions (90 + 7.2) and divide the calculated train length by this relative speed to find the exact time.

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