Multiple choice

In what time the boat cover a distance of 140km upstream? Statement I: A boat covers 30 km downstream in 3 hours. Statement II: The speed of the current is 30 % of its downstream speed.

  1. Statement I alone is sufficient to answer the question

  2. Statement II alone is sufficient to answer the question

  3. Either Statement I or statement II is sufficient to answer the question

  4. Neither Statement I nor statement II is sufficient to answer the question

  5. Both Statements I and II together are necessary to answer the question
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Statement I: Downstream speed = 30/3 = 10 km/h. Statement II: Stream speed = 30% of downstream speed = 0.3 × 10 = 3 km/h. From I and II: If downstream speed = boat + stream = 10, then boat speed in still water = 10 - 3 = 7 km/h. Upstream speed = boat - stream = 7 - 3 = 4 km/h. Time for 140 km upstream = 140/4 = 35 hours. Both statements together are necessary and sufficient.

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