Quantitative Aptitude: Boats and Streams Questions Set 3

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 boat can cover 25 km upstream and 42 km downstream together in 7 hours. Also it can cover 30 km upstream and 63 km downstream together in 9 hours. What is the speed of the boat in still water?
    A) 13 km/hr
    B) 8 km/hr
    C) 7 km/hr
    D) 11 km/hr
    E) 16 km/hr
    View Answer
    Option A
    Solution:

    Upstream speed in both cases is 25 and 30 resp. Ratio is 25 : 30 = 5 : 6. So let times in both cases be 5x and 6x
    Downstream speed in both cases is 42 and 63 resp. Ratio is 42 : 63 = 2 : 3. So let times in both cases be 2y and 3y
    So 5x + 2y = 7
    and 6x + 3y = 9
    Solve both, x = 1, y = 1
    So upstream speed is = 25/5x = 5 km/hr
    And downstream = 42/2y = 21 km/hr
    So speed of boat is 1/2 * (5+21)
  2. A man rows to a certain place and comes back, but by mistake he covers 1/3rd more distance while coming back. The total time for this journey is 10 hours. The ratio of speed of boat to that of stream is 2 : 1. If the difference between upstream and downstream speed is 12km/hr, then how much time will the man take to reach to starting point from his present position?
    A) 35 minutes
    B) 45 minutes
    C) 60 minutes
    D) 40 minutes
    E) 55 minutes
    View Answer
    Option D
    Solution:

    Speed of boat and stream – 2x and x respectively. So downstream speed = 2x+x = 3x, and upstream speed = 2x-x = x
    Let total distance between points is d km
    So he covered d km downstream, and while coming back i.e. upstream he covers d + 1/3 *d = 4d/3 km
    Total time for this journey is 10 hrs. So
    d/3x + (4d/3)/x = 10
    Solve, d = 6x
    Now also given, that (2x+x) – (2x-x) = 12
    Solve, x = 6
    So d = 36 km
    So to come to original point, he will have to cover 1/3 * 36 = 12 km
    And with speed 3x = 18 km/hr(downstream)
    So time is 12/18 * 60 = 40 minutes
  3. A man can row at a speed of 15 km/hr in still water to a certain upstream point and back to the starting point in a river which flows at 9 km/hr. Find his average speed for total journey.
    A) 10.4 km/hr
    B) 8.4 km/hr
    C) 9.1 km/hr
    D) 5.2 km/hr
    E) 9.6 km/hr
    View Answer
    Option E
    Solution:

    When the distance is same, then average speed throughout journey would be:
    Speed downstream * Speed upstream/speed in still water.
    So here average speed = (15+9)*(15-9)/15 = 9.6 km/hr
  4. A boat takes 5 hours for travelling downstream from point A to point B and coming back to point C at 3/4th of total distance between A and B from point B. If the velocity of the stream is 3 kmph and the speed of the boat in still water is 9 kmph, what is the distance between A and B?
    A) 24 km
    B) 32 km
    C) 27 km
    D) 21 km
    E) 34 km
    View Answer
    Option A
    Solution:

    Let total distance from A to B= d km, So CB = 3d/4 km
    So
    d/(9+3) + (3d/4)/(9-3) = 5
    Solve, d = 24 km
  5. At its usual rowing rate, a boat can travel 18 km downstream in 4 hours less than it takes to travel the same distance upstream. But if he the usual rowing rate for his 28-km round trip was 2/3rd, the downstream 14 km would then take 12 hours less than the upstream 14 km. What is the speed of the current?
    A) 1.5 km/h
    B) 3 km/h
    C) 2 km/h
    D) 3.5 km/h
    E) 4 km/hr
    View Answer
    Option B
    Solution:

    Let speed of boat = x km/hr, and of current = y km/hr
    So
    18/(x-y) = 18/(x+y) + 4
    Gives x2 = 9y + y2……..(1)
    Now when speed of boat is 2x/3
    14/(2x/3 -y) = 14/(2x/3 +y) + 12
    42/(2x-3y) = 42/(2x+3y) + 12
    Gives 4x2 = 21y + 9y2…………(2)
    From (1), put value of x2 in (2) and solve
    Solving, x = 6, y = 3
  6. A boat can row to a place 120 km away and come back in 25 hours. The time to row 24 km with the stream is same as the time to row 16 km against the stream. Find the speed of current.
    A) 1.5 km/h
    B) 3 km/h
    C) 2 km/h
    D) 3.5 km/h
    E) 4 km/hr
    View Answer
    Option C
    Solution:

    Downstream speed = 24/x km/hr
    Upstream speed = 16/x km/hr
    120/(24/x) + 120/(16/x) = 25
    Solve, x = 2 km/hr
    So, downstream speed = 12 km/hr, upstream speed = 8 km/hr
    Speed of current = 1/2 * (12 – 8) km/hr
  7. A boatman can row 4 Km along the stream in 20 minutes and return in 24 minutes. Find the speed of boatman in still water.
    A) 10 km/hr
    B) 8 km/hr
    C) 15 km/hr
    D) 12 km/hr
    E) 11 km/hr
    View Answer
    Option E
    Solution:

    Downstream speed = 4/20 * 60 = 12 km/hr
    Upstream speed = 4/24 * 60 = 10 km/hr
    Speed of boatman = 1/2 (12+10) = 11 km/hr
  8. A man can row a certain distance downstream in 3 hours and return the same distance in 9 hours. If the speed of current is 18 km/hr, find the speed of man in still water.
    A) 47 km/hr
    B) 48 km/hr
    C) 42 km/hr
    D) 50 km/hr
    E) 36 km/hr
    View Answer
    Option E
    Solution:

    Use formula:
    B = [tu + td] / [tu – td] * R
    B = [9+3] / [9-3] * 18
    B = 36 km/hr
  9. Four times the downstream speed is 8 more than 15 times the upstream speed. If difference between downstream and upstream speed is 24 km/hr, then what is the ratio of speed in still water to the speed of the current?
    A) 9 : 2
    B) 5 : 3
    C) 7 : 1
    D) 4 : 1
    E) 7 : 3
    View Answer
    Option B
    Solution:

    Let speed in still water = x km/hr, of current = y km/hr
    So
    4 (x+y) = 15(x-y) + 8
    Solve, 11x – 19y + 8 = 0…….(1)
    Also (x+y) – (x-y) = 24
    So y = 12
    Put in (1). x = 20
    So x/y = 20/12 = 5/3
  10. A boat can cover 14 km upstream and 21 km downstream together in 3 hours. Also it can cover 21 km upstream and 42 km downstream together in 5 hours. What is the speed of current?
    A) 13 km/hr
    B) 8 km/hr
    C) 7 km/hr
    D) 11 km/hr
    E) 16 km/hr
    View Answer
    Option C
    Solution:

    Upstream speed in both cases is 14 and 21 resp. Ratio is 14 : 21 = 2 : 3. So let times in both cases be 2x and 3x
    Downstream speed in both cases is 21 and 42 resp. Ratio is 21 : 42 = 1 : 2. So let times in both cases be y and 2y
    So 2x + y = 3
    and 3x + 2y = 5
    Solve both, x = 1, y = 1
    So upstream speed is = 14/2x = 7 km/hr
    And downstream = 21/y = 21 km/hr
    So speed of current is 1/2 * (21-7)

Click here for questions on Boats and Streams

 

Related posts

68 Thoughts to “Quantitative Aptitude: Boats and Streams Questions Set 3”

  1. Sachin Shukla

    hello mam? koi h?

      1. Sachin Shukla

        q1 correct h? mam

        1. EKTA

          yess it is crct…

          1. Sachin Shukla

            30kaha se aaya

          2. EKTA

            sry mene solution nahi dekha .mene orally solve kiya and ans aa gya so

          3. Sachin Shukla

            okk

          4. Sachin Shukla

            A boat can cover 25 km upstream and 42 km downstream together in 7 hours. Also it can cover 40 km upstream and 63 km downstream together in 9 hours. What is the speed of the boat in still water?
            A) 13 km/hr
            B) 8 km/hr
            C) 7 km/hr
            D) 11 km/hr
            E) 16 km/hr
            View Answer
            Option A
            Solution:
            Upstream speed in both cases is 25 and 30 resp. Ratio is 25 : 30 = 5 : 6. So let times in both cases be 5x and 6x
            Downstream speed in both cases is 42 and 63 resp. Ratio is 42 : 63 = 2 : 3. So let times in both cases be 2y and 3y
            So 5x + 2y = 7
            and 6x + 3y = 9
            Solve both, x = 1, y = 1
            So upstream speed is = 25/5x = 5 km/hr
            And downstream = 42/2y = 21 km/hr
            So speed of boat is 1/2 * (5+21)

          5. EKTA

            up dwn time
            25 42 7
            40 63 9
            ——————————

            nw take hcf of downstream 42 and 63 = 21
            so 21 km/hr is downstream speed
            time in downstream= 42 km/21= 2 hr

            as above given 25 up 42 dow total time 7
            if in downtstream time 2 hrs then remaining time in upstream 7-2=5 hr
            upstream speed= 25/5= 5 km/hr

            speed of boat = (21+5)/2= 13 km/hr

          6. _/_

            ye new logic hai?

          7. _/_

            ty
            i like it
            one more qs

          8. _/_

            Four times the downstream speed is 8 more than 15 times the upstream speed. If difference between downstream and upstream speed is 24 km/hr, then what is the ratio of speed in still water to the speed of the current?
            A) 9 : 2
            B) 5 : 3
            C) 7 : 1
            D) 4 : 1
            E) 7 : 3

          9. EKTA

            current speed= (downstream- upstream)/2
            = 24/2=12 km/hr
            4 ( downstream)= 15( upstream)+8
            4( x+ 12) = 15 (x-12) +8
            on solving x=20 km /hr
            boat speed: current speed
            20:12
            5:3

          10. kumkum ahuja

            At its usual rowing rate, a boat can travel 18 km downstream in 4 hours less than it takes to travel the same distance upstream. But if he the usual rowing rate for his 28-km round trip was 2/3rd, the downstream 14 km would then take 12 hours less than the upstream 14 km. What is the speed of the current?
            isko b krna apne usi method se plz mam

          11. _/_

            At its usual rowing rate, a boat can travel 18 km downstream in 4 hours less than it takes to travel the same distance upstream. But if he the usual rowing rate for his 28-km round trip was 2/3rd, the downstream 14 km would then take 12 hours less than the upstream 14 km. What is the speed of the current?
            A) 1.5 km/h
            B) 3 km/h
            C) 2 km/h
            D) 3.5 km/h
            E) 4 km/hr
            View Answer
            Option B

          12. EKTA

            muje ye quest abhi theek se samjh nii aya he …

          13. Oliver Queen

            ye 28 ki jagah kahin 18 to nhi?

          14. EKTA

            i dnt knw..i am weak in these chapters like time nd distance

          15. thinker

            Plz help question smjh Ni aaya .you are genius

          16. _/_

            khan dikkt hai?

          17. thinker

            Ye pura hi smjh Ni as rha

          18. _/_

            wait
            quiz over hone do

          19. thinker

            Ok wese sblog quiz me kahan participate krte h . I also want to participate in grouping quiz.

          20. _/_

            up dwn time
            25 42 7
            40 63 9
            ——————————

            nw take hcf of downstream 42 and 63 = 21
            so 21 km/hr is downstream speed
            time in downstream= 42 km/21= 2 hr

            as above given 25 up 42 dow total time 7
            if in downtstream time 2 hrs then remaining time in upstream 7-2=5 hr
            upstream speed= 25/5= 5 km/hr

            speed of boat = (21+5)/2= 13 km/hr
            ………..
            esme doubt hai na u ko?

          21. thinker

            Nhi dusre me

          22. _/_

            vo mujhe ni aaya

        2. ohh yes

          its 30 km instead 40 km upstream

          1. Sachin Shukla

            waii to mai confuse hu idhar EKTA bol rahi yee correct h..

          2. Sachin Shukla

            mam 10No. qsn same type na

          3. Sachin Shukla

            mam to 1st me 25 42 and 40 63 ka ratio nikalna na?

          4. nhi

            upstreams ka alag se

            n downstreams ka alag se

            25 and 40
            42 and 63
            tabi then x and y me 1 equation bnegi

          5. Sachin Shukla

            s s…

          6. EKTA

            mam this question can be solved in 30 sec without forming equation. as it is time taking

          7. How??

            I will add in solution

          8. EKTA

            up dwn time
            25 42 7
            40 63 9
            ——————————

            nw take hcf of downstream 42 and 63 = 21
            so 21 km/hr is downstream speed
            time in downstream= 42 km/21= 2 hr

            as above given 25 up 42 dow total time 7
            if in downtstream time 2 hrs then remaining time in upstream 7-2=5 hr
            upstream speed= 25/5= 5 km/hr

            speed of boat = (21+5)/2= 13 km/hr

            mam this can be apply

          9. thinker

            Nice yar thanks

      1. EKTA

        mam cudose to u for ur great efforts…mam q 2 niii samjh aa rha muje

        1. thankyou 🙂

          in 2nd::

          Points A to B k bich me travel karna hai
          A to B downstream, then B to A upstream
          But 1/3rd distance aage chli gai boat after A
          now downstream to A to B travel hua
          and then B to A + 1/3rd distance – upstream

          Now is point se vapis A par ana hai – this time is to be found. — and in this downstream speed will be used

          1. EKTA

            thank u mam

  2. EKTA

    8/10… mam quest 5 also nt getting

    1. it is – speed of stream will remain constant
      first the speed of boat was x

      and then 2x/3
      In both cases for different journeys, different time is given

      1. EKTA

        okk mam thank u

  3. Oliver Queen

    Ma’am que 6 right ha?
    kyun ki 2nd condition follow nahi kr rhi same speed se

      1. Oliver Queen

        yes
        ye wali The time to row 21 km with the stream is same as the time to row 12 km against the stream. Find the speed of current.
        dono ki timing alg-2 aa rhi

      2. PHENOMENAL

        thanx maam plzz upload more sets high level

  4. AVI™ (Sinchen loveR)

    thnxxx done

  5. kumkum ahuja

    ty az:)

  6. Pawan

    in question 2 how we will come to know that first he will go downstream and then up .why not reverse..??

  7. Jellyfish

    8/10
    Alternative method que no 10
    21/x+y+14/x-y=3…..1
    42/x+y+21/x-y=3….2
    Solve 1&2 these method correct???

    1. raman

      yes i also followed this method.ans sahi aya..par yeh lenghty ho jata hai

  8. Sourav

    q-6 ka ans 4 aa raha h….

  9. Ayushi Srivastava

    5 que. couldn’t get it ….1st eqn,,18/x-18/y=4;;;; 2nd eqn. 42/2x-14/y=12….how to solve it quickly

    1. Ayushi Srivastava

      x means downstream…y means upstream

Leave a Comment