Aptitude Lectures

These are a list of my Quantitavtive Aptitude Lectures hosted on Youtube @ Aptitude Academy

15 Comments

  1. A man can row 40 km upstream and 55 km downstream in 13 hours. Also, he can row 30 km upstream and 44 km downstream in 10 hours. Find the speed of the man in still water and the speed of the current.
    (1) 5 (2) 3
    (3) 6 (4) 4

    how to solve this

    • hi vineetha,

      in this problem the time and distance is given, so we use time=(distance/speed).
      let speed of upstream=x.
      let speed of downstream=y.
      for 40km upstream, the time=40/x.
      for 55km downstream, time=55/y.

      acc to question, (40/x)+(55/y)=13.

      similarly, (30/x)+(44/y)=10.

      put 1/x=u and 1/y=v.

      eq(1) and (2) will be

      40u+55v=13.
      30u+44v=10.

      solving above equations, we get u=1/5 and v=1/11.
      and as x=1/u, so x=5 and similarly y=11.

      now we know that speed of man in still water=(speed in downstream+speed in upstream)/2
      speed of man in still water=(11+5)/2=8.

      and speed of the current=(speed in downstream-speed in upstream)/2
      speed of current=(11-5)/2=3

  2. Mr.Daniel i am really impressed from your lecture, sir i am expecting another important 8 topics ie; time and dis, %, avg, aligation or mixture, chain rule, calender,clock and area & volume please upload these topics in videos. Because your explanation is very easy to understand. Will you plz do this.
    Thank you

  3. Mr.Daniel i am really impressed from your lecture, sir i am expecting another important 8 topics ie; time and dis, %, avg, aligation or mixture, chain rule, calender,clock and area & volume please upload these topics in videos. Because your explanation is very easy to understand. Will you plz do this.
    Thank you

  4. i like it very much. i would appreciate if u solve my doubts i did given the questions but u did’nt replied yet. plz reply

  6. sir where were you for long time.. i loved your videos, the way you understand the things are quite impressive . do upload the video regular interval. if you make a group in facebook where we can post our query that will be helpful i guess.

    • Hello Parsuram :) You can post the questions on the FB page itself :) Search for it :) And Ill be posting videos every sunday from now on :)

  8. Respected Sir,
    These aptitude videos are very important & useful for those who are preparing for the competitive exam ,it helped me lot & I want you to please upload the video on short cut tricks for solving Simple/Compund Interest Problems.
    Thanks.

  9. Sir ,pls upload the boats &streams and another concepts remaining parts because ur lessons very helpful for many peoples like me.pls pls ……

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