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: 6 years ago | Updated: 1 year ago

Updated: 1 year 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)

ব্যাখ্যা

1.7k

Best Ans:

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}}}

6 years ago

0 0

Md Azizur Rahman

Founder of Satt

গড় (Average)