The speed of a boat down stream is 150% more than its speed upstream. If the time taken by the boat for going 80 km downstream and 50 km upstream is 8.2 hours, then what is the speed (in km/h) of the boat down stream?

25

The ratio of upstream speed to downstream speed 

= 100x ∶ 250x = 2x ∶ 5x

according to the question,

\(\frac{80}{5x}\)+ \(\frac{50}{2x}\)= 8.2 hours

= \(\frac{16}{x}\)+ \(\frac{25}{x}\)= 8.2  

= \(\frac{41}{x}\)= 8.2

= x = \(\frac{41}{8.2}\)

= x = 5 

So,

The speed downstream of the boat = 5x

= 5x = 5 × 5 =25 km/h