Question

The speed of a boat downstream 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 downstream?
1. 25
2. 16
3. 24
4. 30

Answer 1

Correct Answer - Option 1 : 25

Given:

Speed of the boat downstream = 150% more than speed upstream

Formulas used:

Distance/Speed = Time 

Calculation:

Let the speed upstream = 100a 

⇒ Speed of the boat downstream = 100a × 250/100 = 250a 

As per the question; 

80 km/250a + 50 km/100a = 8.2 hours 

⇒ 8/25a + 1/2a = 82/10 

⇒ (16 + 25)/50a = 41/5 

⇒ 41/50a = 41/5 

⇒ 1/10a = 1

⇒ a = 1/10 

∴ The speed downstream of the boat = 250a

⇒ 250a = 250 × 1/10 

⇒ 25 km/h