Question

A Boat covers upstream in 12 Hours 48 minutes to travel distance from Point A to B, while it takes 6 hours to cover 3/4th of the same distance running downstream. The speed of the current is 15 Km/hr. The boat covered both forward distance from A to B and backward distance from B to A. Then what is the distance between A and B?​

Answer 1

Answer:640

Step-by-step explanation:

1. The basic formula for this types of question is Δv=$\frac{d}{t}$

• Velocity of boat - Velocity of stream = d ÷ (time travelling upstream)

• Velocity of boat + Velocity of stream = $\frac{3}{4}$d ÷ (time travelling downstream)

Then convert the time in hours

12.48 hours = 12 + (48÷60) = 12.8 hours Note this step

Now the Equations are

1. Vboat - Vstream = d ÷ 12.8                                       EQN 1
2. Vboat + Vstream = $\frac{3}{4}$ ÷ 6            EQN 2

Substact EQN 1 from EQN 2 we get

• 2 Vstream = d { $\frac{3}{4*6}$ - $\frac{1}{12.8}$ }
• 2 Vstream = d * 0.046875
• d = 2 * Vstream / 0.046875

As Vstream is given 15 Km/hr

After solving we get d = 640 Km  as answer.