If a man swims 4 miters upstream at 1 mph and back downstream to the same point at 4 mph, what is his average speed?

Created: 7 years ago | Updated: 3 months ago

Updated: 3 months ago

0.8 mph

1.6 mph

2.4 mph

3.2 mph

বিসিএস প্রিলিমিনারি + রিটেন টেস্ট ২৮ তম বিসিএস প্রিলিমিনারি টেস্ট (28-11-2008) গণিত গড় (Average)

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Best Ans:

প্রশ্ন: If a man swims 4 miters upstream at 1 mph and back downstream to the same point at 4 mph, what is his average speed?

Let towards upstream he swims at v1 mph and towards downstream he swims at v2 mph . '. v1 = 1 and v2 = 4 Now, his average speed

$= \frac{2}{\frac{1}{v_{1}} + \frac{1}{v_{2}}} = \frac{2}{\frac{1}{1} + \frac{1}{4}} = \frac{2}{1 + \frac{1}{4}} = \frac{2}{\frac{5}{4}} = \frac{2}{\frac{5}{4}} = 2 \times \frac{4}{3} = \frac{8}{5} = 1.6 m p h [R u l e o f h a r m o n i c m e a n] T o t a l 5 m p h s w i m s 8 m i t r e s 5 |8| 1.6 m p h \frac{5}{\frac{30}{\frac{30}{\times}}}$

7 years ago

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