Multiple choice

Each of given questions consists of a question followed by informations in three statements. You have to study the question and the statements and decide that information in which of the statement(s) is/are necessary to answer the question. Find track length I. A and B start from X and Y on a track respectively. They move towards each other and meet at 40 meters from X. II. After continuing their journey they made a return and meet at 25 meters from Y. III. Speed of A is 25m/s.

  1. Only I

  2. Only II

  3. I and II together

  4. II and III

  5. None of them are sufficient
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let track length = L. First meeting at 40m from X means A traveled 40, B traveled (L-40). Second meeting at 25m from Y means A traveled L+25, B traveled 2L-25. From first meeting: distance ratio = speed ratio = 40:(L-40). From second meeting: (L+25):(2L-25) = 40:(L-40). Solving: (L+25)/(2L-25) = 40/(L-40) → (L+25)(L-40) = 40(2L-25) → L² - 15L - 1000 = 80L - 1000 → L² - 95L = 0 → L(L-95) = 0 → L = 95m. So I and II together are sufficient; III (A's speed) is not needed.

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