Quantitative Aptitude: Boats and Streams Questions Set 5

Boats and Streams Questions for IBPS PO, IBPS Clerk, IBPS RRB, SBI, LIC, IPPB, RBI and other exams. Boats and Streams Questions Bank PO.

  1. A man can row 40 kmph in still water and the river is running at 10 kmph. If the man takes 2 hr to row to a place and back, how far is the place?
    A) 38km
    B) 37.5km
    C) 40.75km
    D) 41km
    E) None
    View Answer
    Option B
    Solution:

    Given u=40 , v=10
    D= t[(u2-v2)/2u]
    =2*[(402-102)/2*40]
    =2*(1600-100)/80
    2*1500/80==>37.5km
  2. A man rows to a place 60 km distant and come back in 35 hours. He finds that he can row 4 km with the stream in the same time as 3 km against the stream. Find the speed in still water and in stream:
    A) 1.5, 2
    B) 0.5, 2.5
    C) 3.5, 0.5
    D) 2, 2.5
    E) None
    View Answer
    Option C
    Solution:

    If he moves 4 km downstream in x hours.
    Downstream speed=4/x
    Upstream speed=3/x
    Then 60/(4/x) + 60/(3/x)=35
    60[(3x+4x)/12]=35
    60*7x/12=35
    5*7x=35==> x=1km.
    Then Downstream speed=4km/hr , Upstream speed=3km/hr
    U=(4+3)/2=7/2=3.5km/hr
    V=(4-3)/2=1/2=0.5km/hr
  3. Speed of a boat in standing water is 12 kmph and the speed of the stream is 3 kmph. A man rows to a place at a distance of 6300 km and comes back to the starting point. The total time taken by him is:
    A) 1120hrs
    B) 1000hrs
    C) 980hrs
    D) 850hrs
    E) None
    View Answer
    Option A
    Solution:

    Downstream speed = (12 + 3) = 15 km/hr
    Upstream speed = (12 – 3) = 9 km/hr
    Total time taken =6300/15+6300/9
    =420+700==>1120hrs.
  4. A boat takes 26 hours for travelling downstream from point A to point B and coming back to point C midway between A and B. If the velocity of the stream is 4 km/hr and the speed of the boat in still water is 10 km/hr, what is the distance between A and B?
    A) 210km
    B) 185km
    C) 140km
    D) 168km
    E) None
    View Answer
    Option D
    Solution:
    Downstream speed = 10+4 = 14
    Upstream speed = 10-4 = 6
    Now total time is 26 hours
    If distance between A and B is d, then distance BC = d/2
    Now distance/speed = time, so
    d/14 + (d/2)/6= 26
    13d/84=26
    Solve, d = 168 km
  5. At his usual rowing rate, Rahul can travel 12 miles downstream in a certain river in 6 hours less than it takes him to travel the same distance upstream. But if he could double his usual rowing rate for his 24-mile round trip, the downstream 12 miles would then take only one hour less than the upstream 12 miles. What is the speed of the current in miles per hour?
    A) 2 2/3mph
    B) 2mph
    C) 1 1/4mph
    D) 3mph
    E) None
    View Answer
    Option A
    Solution:

    Let the speed of Rahul in still water be x mph
    and the speed of the current be y mph
    Then, Speed upstream = (x – y) mph
    Speed downstream = (x + y) mph
    Distance = 12 miles
    Time taken to travel upstream – Time taken to travel downstream = 6 hours
    12/(x-y) – 12/(x+y)=6
    x2=y2+4y—1
    Now he doubles his speed. i.e., his new speed = 2x
    Now, Speed upstream = (2x – y) mph
    Speed downstream = (2x + y) mph
    In this case, Time taken to travel upstream – Time taken to travel downstream = 1 hour
    12/(2x-y) – 12/(2x+y) = 1
    4x2=y2+24y—2
    From 1 and 2 we get
    4y+y2=(24y +y2)/4
    Y=8/3==> 2 2/3mph
  6. There is a road beside a river. Two friends started from a place A, moved to a temple situated at another place B and then returned to A again. One of them moves on a cycle at a speed of 6 km/hr, While the other sails on a boat at a speed of 8 km/hr. If the river flows at the speed of 6 km/hr, which of the two friends will return to place A first?
    A) Cyclist
    B) Sailor
    C) Both come at same time
    D) Anyother
    E) None
    View Answer
    Option A
    Solution:

    Average speed of the cyclist =6 km/hr
    Downstream speed=8+6=14 km/hr
    Upstream speed =8−6=2 km/hr
    Therefore, average speed of the sailor
    =2*14*2/(14+2)
    =3.5km/hr
    Average speed of the cyclist is more than that of the sailor. Therefore, the cyclist will return first.
  7. A boat running upstream takes 8 hours 48 minutes to cover a certain distance, while it takes 4 hours to cover the same distance running downstream. What is the ratio between the speed of the boat and speed of the water current respectively?
    A) 5:4
    B) 8:3
    C) 7:6
    D) 4:5
    E) None
    View Answer
    Option B
    Solution:

    Let the man’s rate upstream be x kmph and that downstream be y kmph.
    Then, distance covered upstream in 8 hrs 48 min = Distance covered downstream in 4 hrs.
    X*8 4/5 =4y
    44/5x=4y
    Y=11/5x.
    Required ratio (y+x)/2=(y-x)/2
    16x/10:6x/10
    8:3
  8. A man takes thrice as long to row a distance against the stream as to row the same distance in favour of the stream. The ratio of the speed of the boat (in still water) and the stream is:
    A) 2:1
    B) 3:2
    C) 1:2
    D) 2:3
    E) None
    View Answer
    Option A
    Solution:

    Lets upstream be xkm/hr
    Downstream be 3x km/hr
    U: V=(3x+x)/2: (3x-x)/2
    4x/2:2x/2
    2:1
  9. A boat running downstream covers a distance of 40km in 4hrs and covering the same distance upstream in 8hrs. What is the speed of a boat in still water.
    A) 6km/hr
    B) 7km/hr
    C) 7.5km/hr
    D) 8.5km/hr
    E) None
    View Answer
    Option C
    Solution:

    Downstream speed=40/4=10km/hr
    Upstream speed=40/8=5km/hr
    So speed of boat in still water=(10+5)/2=15/2
    =7.5km/hr
  10. A boat can travel 3.5km upstream in 14min. If the ratio of the speed of the boat in still water to the speed of the stream is 7:2. How much time will the boat take to cover 36km downstream ?
    A) 65min
    B) 80min
    C) 75min
    D) 70min
    E) None
    View Answer
    Option B
    Solution:

    Speed = 7x:2x
    Downstream = 9x; upstream = 5x
    Upstream speed = 3.5*60/14 = 15kmph
    5x = 15
    x = 3
    Downstream = 9*3 = 27
    Time taken for 36km = 36*60/27 = 80min

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4 Thoughts to “Quantitative Aptitude: Boats and Streams Questions Set 5”

  1. Ap

    Solving first question. Inthis way wrong??
    X/30-x/50=2

  2. kumkum ahuja

    ty mam 🙂

  3. Nishu

    Any shortcut method of Q5 ? …..

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