If sum of upstream and downstream speed of a boat is 82 kmph, and the boat travels 105 km. upstream in 3 hr, Find the time taken by boat to cover 126 km downstream.

Question

নিচের অপশন গুলা দেখুন

• 2.8 hrs
• 2.7 hrs
• 2.5 hrs
• 2.6 hrs

Answer 1

সঠিক উত্তর হচ্ছে: 2.7 hrs

ব্যাখ্যা:

Let Speed of boat in still water = b

Let Speed of still water = w

Then we know that,

Speed of Upstream = U = boat - water

Speed of Downstream = D = boat + water

Given, U + D = 82

b - w + b + w = 82

2b = 82

=> b = 41 kmph

From the given data,

41 - w = 105/3 = 35

w = 6 kmph

Now,

b + w = 126/t

=> 41 + 6 = 126/t

=> t = 126/47  = 2.68 hrs.