17
Q:

Amith can row a boat d km upstream and the same distance downstream in 5 hours 15 minutes. Also, he can row the boat 2d km upstream in 7 hours. How long will it take to row the same distance 2d km downstream for Amith ?

A) 4 hrs 10 min B) 3 hrs 15 min
C) 3 hrs 30 min D) 4 hrs 1 min

Answer:   C) 3 hrs 30 min



Explanation:

Let the speed of boat and stream be x and y kmph respectively.

According to question

d/x+y + d/x-y = 5h 15m or 21/4 hrs ......(i)

and 2d/x-y = 7...... (ii)

From eq. (i) and (ii)

2d/x+y = 7/2

Hence, Amith will take to row 2d km distance downstream in 7/2 hrs

= 3.5 hrs

= 3 hrs 30 min.

Q:

A boat can go 3.6 km upstream and 5.4 km downstream in 54 minutes, while it can go 5.4 km upstream and 3.6 km downstream in 58.5 minutes. The time (in minutes) taken by the boat in going 10 km downstream is:

 

A) 48 B) 50
C) 45 D) 54
 
Answer & Explanation Answer: B) 50

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0 425
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)
 
Answer & Explanation Answer: D) 3(4 + √17)

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2 378
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
 
Answer & Explanation Answer: A) 0.20 Hz

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1 602
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
 
Answer & Explanation Answer: D) 4 s

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0 590
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
 
Answer & Explanation Answer: A)  5

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0 705
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
 
Answer & Explanation Answer: B) 2 kmph

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1 746
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
 
Answer & Explanation Answer: B) 12

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4 1329
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
 
Answer & Explanation Answer: A) 3.5

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1 1062