Subject: General Aptitude · Chapter: Problems on Trains · Exam: · Marks: · Difficulty:
How much time will the train A take to cross an- other train B running in opposite direction? I. Train A crosses a signal pole in 6 seconds. II. Ratio of the speeds of trains A and B is 3 : 2. III. Length of the two trains together is 500 metres.
(a)I only
(b)II only
(c)III only
(d)I or II only
(e)Question cannot be answered even with the information in all the three statements.
Answer
Answer (as printed): E
Explanation
II. Let the speeds of A and B be 3x m / sec and 2x m / sec. I. Length of train A = (3x × 6) m = 18x metres. III. Length of train B = (500 – 18x) m. Relative speed = (3x + 2x) m / sec = 5x m / sec. Sum of their lengths 500 Time taken A to cross B = = sec. Relative speed 5x Thus, even with the information in all the three statements, question cannot be answered. ∴ Correct answer is (e).
Explanation as extracted from the printed page; notation may be imperfect.