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Alex and Hales started rowing towards one another at constant speeds and met after rowing for an hour. The initial distance between Alex and Hales was 20 kilometers and Alex rowed downstream while Hales rowed upstream during this journey. On some other day, the time taken by Alex alone, rowing at the same constant speed, to cover the distance between these two points going upstream was 75 minutes more than the time taken by him to cover the same distance going downstream. What was the time taken in hours by Hales to cover 20 kilometers going upstream? Assume the speed of the stream to be 4 kilometers per hour
  • a)
    1.25
  • b)
    1.6
  • c)
    2.5
  • d)
    5
  • e)
    8
Correct answer is option 'D'. Can you explain this answer?
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Alex and Hales started rowing towards one another at constant speeds a...
Given:
- Alex and Hales started rowing towards one another at constant speeds and met after rowing for an hour.
- The initial distance between Alex and Hales was 20 kilometers.
- Alex rowed downstream while Hales rowed upstream during this journey.
- The speed of the stream is 4 kilometers per hour.
- On some other day, the time taken by Alex alone, rowing at the same constant speed, to cover the distance between these two points going upstream was 75 minutes more than the time taken by him to cover the same distance going downstream.

To find: The time taken in hours by Hales to cover 20 kilometers going upstream.

Assumptions:
Let the speed of Alex be A, and the speed of Hales be H.
The speed of Alex downstream = A + 4
The speed of Alex upstream = A - 4
The speed of Hales upstream = H - 4

Calculation:
1. Let us assume that Alex covered x kilometers downstream in the first hour of rowing and Hales covered (20 - x) kilometers upstream.
2. As the speeds are constant, we can write the equation: x/(A + 4) = (20 - x)/(H - 4)
3. Solving this equation, we get x = (40H - 64A - 320)/(3H + 3A)
4. Now, the time taken by Alex to cover x kilometers downstream at a speed of (A + 4) is x/(A + 4) hours.
5. The time taken by Alex to cover (20 - x) kilometers upstream at a speed of (A - 4) is (20 - x)/(A - 4) hours.
6. As per the question, the time taken by Alex upstream is 75 minutes more than the time taken by Alex downstream. So we can write the equation: (20 - x)/(A - 4) = x/(A + 4) + 75/60
7. Substituting the value of x from step 3, we get (20 - (40H - 64A - 320)/(3H + 3A))/(A - 4) = (40H - 64A - 320)/(3H + 3A(A - 4)) + 5/4
8. Solving this equation, we get H = 5 km/hr
9. The time taken by Hales to cover 20 km upstream at a speed of (H - 4) is 20/(5 - 4) = 20 hours.

Therefore, the answer is option D) 5.
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Alex and Hales started rowing towards one another at constant speeds a...
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Alex and Hales started rowing towards one another at constant speeds and met after rowing for an hour. The initial distance between Alex and Hales was 20 kilometers and Alex rowed downstream while Hales rowed upstream during this journey. On some other day, the time taken by Alex alone, rowing at the same constant speed, to cover the distance between these two points going upstream was 75 minutes more than the time taken by him to cover the same distance going downstream. What was the time taken in hours by Hales to cover 20 kilometers going upstream? Assume the speed of the stream to be 4 kilometers per houra)1.25b)1.6c)2.5d)5e)8Correct answer is option 'D'. Can you explain this answer?
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Alex and Hales started rowing towards one another at constant speeds and met after rowing for an hour. The initial distance between Alex and Hales was 20 kilometers and Alex rowed downstream while Hales rowed upstream during this journey. On some other day, the time taken by Alex alone, rowing at the same constant speed, to cover the distance between these two points going upstream was 75 minutes more than the time taken by him to cover the same distance going downstream. What was the time taken in hours by Hales to cover 20 kilometers going upstream? Assume the speed of the stream to be 4 kilometers per houra)1.25b)1.6c)2.5d)5e)8Correct answer is option 'D'. Can you explain this answer? for GMAT 2024 is part of GMAT preparation. The Question and answers have been prepared according to the GMAT exam syllabus. Information about Alex and Hales started rowing towards one another at constant speeds and met after rowing for an hour. The initial distance between Alex and Hales was 20 kilometers and Alex rowed downstream while Hales rowed upstream during this journey. On some other day, the time taken by Alex alone, rowing at the same constant speed, to cover the distance between these two points going upstream was 75 minutes more than the time taken by him to cover the same distance going downstream. What was the time taken in hours by Hales to cover 20 kilometers going upstream? Assume the speed of the stream to be 4 kilometers per houra)1.25b)1.6c)2.5d)5e)8Correct answer is option 'D'. Can you explain this answer? covers all topics & solutions for GMAT 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Alex and Hales started rowing towards one another at constant speeds and met after rowing for an hour. The initial distance between Alex and Hales was 20 kilometers and Alex rowed downstream while Hales rowed upstream during this journey. On some other day, the time taken by Alex alone, rowing at the same constant speed, to cover the distance between these two points going upstream was 75 minutes more than the time taken by him to cover the same distance going downstream. What was the time taken in hours by Hales to cover 20 kilometers going upstream? Assume the speed of the stream to be 4 kilometers per houra)1.25b)1.6c)2.5d)5e)8Correct answer is option 'D'. Can you explain this answer?.
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