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Doctors Medicines MCQs Q&A

  1. 12 km/hr
  2. 10 km/hr
  3. 18 km/hr
  4. 15 km/hr
  5. None of these
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1 Answers

Option 4 : 15 km/hr

Let speed of fairy in still water be x km/hr

Time = 3 hour 20 min = 3 + 20/60 = 10/3

According to question;

24/(x + 3) + 24/(x - 3) = 10/3

⇒ (24x - 72 + 24x + 72)/ = 10/3

⇒ 144x = 10x2 - 90

⇒ 10x2 - 144x - 90 = 0

On solving,

x = 15 km/hr
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