22
Q:

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.

 A) 2.8 hrs B) 2.7 hrs C) 2.6 hrs D) 2.5 hrs

Explanation:

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.

Q:

In a stream running at 3 km/h, a motorboat goes 12 km upstream and back to the starting point in 60 min. Find the speed of the motor boat in still water. (in km/h)

 A) 2(2 + √17) B) 3(2 + √17) C) 2(4 + √15) D) 3(4 + √17)

Explanation:

0 614
Q:

A boat at anchor is rocked by waves whose consecutive crests are 125 m apart. The velocity of the wave of the moving crests is 25 m/s. What is the frequency of the rocking of the boat?

 A) 0.20 Hz B) 625 Hz C) 250 Hz D) 100 Hz

Explanation:

1 736
Q:

If an anchored boat is rocked by waves whose crests are 80 m apart and whose velocity is 20 m/s, then the time required by the crests to reach the boat is ___.

 A) 0.5 s B) 5 s C) 0.2 s D) 4 s

Explanation:

1 733
Q:

A boat covers a distance of 14 km upstream and 16 km downstream in 9 hours. It covers a distance of 12 km upstream and 40 km downstream in 11hours. What is the speed (in km/hr) of the boat in still water?

 A)  5 B)  2 C)  3 D) 4

Explanation:

0 946
Q:

A man, rowing a boat, covers a distance of 16 km in two hours downstream. He covers half the distance in same amount of time when rowing upstream. Calculate the speed of the stream.

 A) 4 kmph B) 2 kmph C) 3 kmph D) 1 kmph

Explanation:

1 969
Q:

A boat covers 143 km upstream in 13 hours and the same distance downstream in 11 hours. What is the speed (in km/hr) of the boat in still water?

 A) 10 B) 12 C) 14 D) 8

Explanation:

4 1410
Q:

A boat cover row 12 km upstream in 4 hours and can cover the same distance downstream in 3 hours. What is the speed (in km/hr) of the boat in still water?

 A) 3.5 B) 3 C) 2.5 D) 2

Explanation:

1 1284
Q:

The upstream speed of the boat is 40 kmph and the speed of the boat in still water is 55 kmph. What is the downstream speed of the boat?

 A) 75 kmph B) 70 kmph C) 60 kmph D) 65 kmph

Explanation: