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    Tutor MathsGuru: Ask me for your burning Maths questions!

    Scheduled Pinned Locked Moved Primary Schools - Academic Support
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    • I Offline
      IknowIcan
      last edited by

      Vanilla Cake:
      firebird:

      Dear maths guru

      Please help me on the following maths:

      Hi Firebird,
      Pls refer to the below workings done by Vanilla Cake, this morning. Due to time constraint, she didn't complete the speed question(she was in a rush to go to school). Sorry, pls wait for others like Dharma etc to help.If you don't mind, could you pls advise the source of these questions? The ones on ratio and speed are interesting and I will let DD2 to practise.
      Thks.

      VC's mum
      firebird:
      1) John had $180 more than Raymond at first. Both bought a different printer with some of their money. In the end Rayamond was left with $20 more than John. If John's printer cost 50% more than Raymond's printer, how much does John's printer cost?
      John's printer-> 150%
      Raymond's printer -> 100%
      $(180+20)= $200
      50% -> $200
      150% -> $600

      Cost of John's printer = $600
      firebird:
      2) At 9am John was cycling from Point A to Point B. At the same time, Mary was cycling from point B to point A using the same route as John. Cycliing at a speed of 4km/h faster than Mary, they would pass each other 300 meter away from the mid point.
      a) What time did they pass each other?
      b) If John took another 3 minutes to reach Point B, what time would Mary reach Poin A?
      0.3/4 = 0.075 h = 4.5 min
      Add 4.5 min to 9 am -> 9:04:30
      (a) They passed each other at 9:04:30

      (b) Not enough time to think and solve, pls wait for others to solve.
      firebird:
      3) Daniel had 40% more stickers than Brandon. Daniel and Brandon each gave 20% of their stickers to Calvin. As a result, Calvin's stickers increased by 80%. If Daniel has 20 more stickers than Calvin in the end, how many stickers did Brandon have at first?
      Before
      😧 140%
      B: 100%
      πŸ˜„ u

      After
      😧 112%
      B: 80%
      πŸ˜„ u+28%+20% = u+48%

      80% increased for C-> 180/100xu = 1.8u

      1.8u=u+48%
      0.8u=48%
      u=60%

      πŸ˜„ 60%+48% = 108%
      Difference between D and C -> D-C=112%-108% = 4%
      4% -> 20
      100% -> 20/4x100=500

      At first, Brandon had 500 stickers.
      firebird:
      4) At a conference made up of speakers and participants, there were 20% more men than women. The ratio of male speakers to female speakers was 8:5. There was an equal number of male and female participants.
      a) Find the ratio of male speakers to male participants at the conference.
      b) Halfway, 40 male participants left the conference and another 60 female participants joined the conference. In the end, there were 3/4 as many male participants remaining behind. How many speakers were there at the conference?
      This is a trick question and you have to know the common difference is 3u as the number of male and female participants was the same.

      Total
      M : W
      120 : 100
      6 : 5
      18: 15

      Speakers
      M : W
      8 : 5
      Total speakers = 13u (8u+5u)

      Participants
      M : W
      10 : 10

      8: 10
      (a) Ratio of male speakers to male participants = 8 : 10 = 4 : 5

      I use cross multiplication to solve this, you may wish to use alternative methods to suit you.

      (10u-40)/(10u+60)=3/4
      30u+180=40u-160
      10u=340
      u=34
      13u=442

      Number of speakers at the conference = 442

      Check
      Speakers
      M: 272
      W: 170

      Participants
      M: 340
      F: 340

      Total
      M: 612
      W: 510

      Phew, done except for speed part (b).Pls check all my calculations, thanks.

      Hi there, for the above question on Speed, we need to take into consideration the time traveled by Mary as well. There is a difference of 300m which takes 4.5 mins to travel. Assuming they start at 9am at the same time, John traveled 4km/h faster than Mary which gives him a head start of 300m. Thus, Mary and John would have traveled for 9mins while John traveled 300m more. The answer should be 9:09am instead.

      How do you solve part b?

      1 Reply Last reply Reply Quote 0
      • D Offline
        Dharma
        last edited by

        Vanilla Cake:
        Pls :imdrowning: and TIA for your time cum effort.


        http://i51.tinypic.com/34qoejc.jpg\">
        Answer given: 2010
        (1 + 1/2) x (1 + 1/(2)^2)
        = (1 + 1/((2)^2)^0 ) x (1 + 1/((2)^2)^1 )
        = 3/2 x 5/4 = 15/8
        = 2 - 1/8
        = 2(1 - 1/16)
        = 2(1 - 1/((2)^2)^2 )

        (1 + 1/2) x (1 + 1/(2)^2) x ( (1 + 1/(2)^4)
        =(1 + 1/((2)^2)^0 ) x (1 + 1/((2)^2)^1 ) x ( (1 + 1/((2)^2)^2 )
        = 3/2 x5/4 x 17/16 = 255/128
        = 2 - 1/128
        = 2(1 - 1/256)
        = 2(1 - 1/((2)^2)^3 )



        (1 + 1/2) x (1 + 1/(2)^2) x ( (1 + 1/(2)^4) x .... x ( (1 + 1/((2)^2)^2009)
        = 2(1 - 1/((2)^2)^(2009 +1) )
        = 2(1 - 1/((2)^2)^(2010) )

        n = 2010

        1 Reply Last reply Reply Quote 0
        • T Offline
          Tania
          last edited by

          Hi, I have one qn. Kindly help.


          Mary took x hours to travel from Town A to Town B while Peter took y hours to travel from Town B to Town A. If both of them started their journey at 10am at what time will they meet each other on the way??

          Thanks!

          1 Reply Last reply Reply Quote 0
          • CoffeeCatC Offline
            CoffeeCat
            last edited by

            Tania:
            Hi, I have one qn. Kindly help.


            Mary took x hours to travel from Town A to Town B while Peter took y hours to travel from Town B to Town A. If both of them started their journey at 10am at what time will they meet each other on the way??

            Thanks!
            Speed of Mary -> 1/x journey per hr
            Speed of Peter -> 1/y journey per hr
            Combined Speed -> 1/x + 1/y = (x+y)/xy journey per hour
            Hence Time taken -> 1/combinedspeed = xy/(x+y)
            Hmm..its kinda weird to express a timing in algebra...

            1 Reply Last reply Reply Quote 0
            • W Offline
              wdiong
              last edited by

              Hi, I wld like help with this P3 question:


              Ali had 3 times as many marbles as Bala. After Ali lost 4 marbles and gave Bala some marbles, the 2 boys have the same number of marbles. Bala has 22 marbles now. How many marbles did Bala have at first?

              1 Reply Last reply Reply Quote 0
              • Y Offline
                yingxuan0806
                last edited by

                wdiong:
                Hi, I wld like help with this P3 question:


                Ali had 3 times as many marbles as Bala. After Ali lost 4 marbles and gave Bala some marbles, the 2 boys have the same number of marbles. Bala has 22 marbles now. How many marbles did Bala have at first?
                Total marbles -> 22x2=44 ( bala has 22 now. they have the same number of marbles now so multiply by 2)
                at first, ali 3u, bala 1u
                4u -> 44
                1u -> 44/4=11

                hope you get it now.. πŸ˜ƒ

                1 Reply Last reply Reply Quote 0
                • H Offline
                  Herbie
                  last edited by

                  hi vanilla cake, may i ask the questions which u hv posted on s1 and n question are they pri sch maths?? Please advice… Tq

                  1 Reply Last reply Reply Quote 0
                  • W Offline
                    wdiong
                    last edited by

                    yingxuan0806:
                    wdiong:

                    Hi, I wld like help with this P3 question:


                    Ali had 3 times as many marbles as Bala. After Ali lost 4 marbles and gave Bala some marbles, the 2 boys have the same number of marbles. Bala has 22 marbles now. How many marbles did Bala have at first?

                    Total marbles -> 22x2=44 ( bala has 22 now. they have the same number of marbles now so multiply by 2)
                    at first, ali 3u, bala 1u
                    4u -> 44
                    1u -> 44/4=11

                    hope you get it now.. πŸ˜ƒ

                    Hi,
                    Thanks for trying to work out but I've found the solution to this problem from someone else:

                    Work backwards-
                    22 x 2 = 44
                    44 + 4= 48
                    48 /4 = 12

                    1 Reply Last reply Reply Quote 0
                    • F Offline
                      fxchow
                      last edited by

                      Hi,


                      Please help in this question. TIA πŸ˜„

                      Mac and Sue share some stickers.
                      If Mac gives Sue 1/2 of his stickers, Sue will have 56 more stickers than Mac.
                      If Mac gives 1/4 of his share to Sue, Sue will have 26 more stickers than Mac.
                      How many stickers does Mac have at first?
                      Ans: 60

                      1 Reply Last reply Reply Quote 0
                      • MathIzzzFunM Offline
                        MathIzzzFun
                        last edited by

                        fxchow:
                        Hi,


                        Please help in this question. TIA πŸ˜„

                        Mac and Sue share some stickers.
                        If Mac gives Sue 1/2 of his stickers, Sue will have 56 more stickers than Mac.
                        If Mac gives 1/4 of his share to Sue, Sue will have 26 more stickers than Mac.
                        How many stickers does Mac have at first?
                        Ans: 60
                        Hi fxchow,

                        Hope this helps - http://www.flickr.com/photos/62167097@N02/5743271554/in/photostream

                        cheers.

                        1 Reply Last reply Reply Quote 0

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