Multiple choice

Directions: The following question is accompanied by two statements A and B. You have to determine which statements(s) is/are sufficient/necessary to answer the question. There are two trains A and B. If five more compartments of length 14 m each are attached to the longer train, then in what time does train A and train B cross each other running in opposite directions? (A) The ratio of the length of train A to that of train B was 6 : 7 before additional five compartments were attached to the longer train. The speed of longer train was 76 km/hr and the speed of the shorter train was (25/19)th of the speed of the longer train. (B) Both the trains cross each other in 39 sec before additional five compartments were attached to the longer train when they were running in same direction.

  1. Statement A alone is sufficient to answer the question, but statement B alone is not sufficient to answer the question.

  2. Statement B alone is sufficient to answer the question, but statement A alone is not sufficient to answer the question.

  3. Either statement A or statement B by itself is sufficient to answer the question.

  4. Both the statements taken together are necessary to answer the questions, but neither of the statements alone is sufficient to answer the question.

  5. Statements A and B taken together are not sufficient to answer the question.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Statement A gives speeds and relative length ratio. Statement B gives time to cross in same direction. Both are needed to find the original lengths and then the new time.

AI explanation

To find the crossing time running in opposite directions, we need the lengths of both trains and their relative speed. Statement A provides the speed of train B as 76 km/hr and train A as (25/19) multiplied by 76, which equals 100 km/hr, so the opposite relative speed is 176 km/hr. Statement A also gives the ratio of lengths as 6 to 7, meaning the longer train is train A, but without actual lengths, we cannot determine the new time after adding compartments. Statement B provides the time (39 sec) to cross in the same direction, which gives an equation using relative speed and total length. We must combine statement A and statement B to find the exact lengths of the trains, add the 70 meters from the five compartments to train A, and calculate the new time. Therefore, both statements taken together are necessary to answer the questions.

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