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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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    • D Offline
      Dharma
      last edited by

      free willy:
      I don't know how to help my P6 boy with this homework question. He miss the class cause he had to go for tournment.


      Box A has 200 red balls and 90 blue balls. Box B has 80 red balls and 100 blue balls. How many red balls and blue balls need to be moved from box A to Box B so that there are 80%of red balls in box A and 50% of blue balls in box B.
      Box A
      Red – 200/280 = 71.43%
      Blue – 90/190 = 47.36%

      How can you transfer red and blue balls out of Box A and into Box B and end up with higher percentages of balls in Box A… i.e. 80% of red balls and 50% of blue balls in Box A?

      Think the question typed out wrongly ….. should from box B to box A , instead.

      1 Reply Last reply Reply Quote 0
      • V Offline
        Vanilla Cake
        last edited by

        free willy:
        Box A has 200 red balls and 90 blue balls. Box B has 80 red balls and 100 blue balls. How many red balls and blue balls need to be moved from box A to Box B so that there are 80%of red balls in box A and 50% of blue balls in box B.
        Hi free willy,

        Your question is similar to RGPS P6 SA1 2009 P2 Q18 and the model solution had been provided by http://www.postimage.org/image.php?v=aVNZHuS on 22 Mar 2010.
        Tang had also provided his http://www.kiasuparents.com/kiasu/forum/viewtopic.php?t=280&postdays=0&postorder=asc&start=1170 on 19 Mar 2010.

        Using simultaneous equation to solve while waiting for Mathsguru's model solution.

        Final scenario
        Box A
        Red balls : Blue balls
        4 : 1 (80% : 20%)

        Box B
        Red balls : Blue balls
        1 : 1 (50% : 50%)

        4A+B = 200+80 = 280
        A+B = 90+100 = 190

        3A = 90
        A = 30
        B = 190-30=160

        Final scenario
        Box A
        Red balls : Blue balls
        120 : 30

        Box B
        Red balls : Blue balls
        160 : 160

        Before scenario
        Box A
        Red balls : Blue balls
        200 : 90

        Box B
        Red balls : Blue balls
        80 : 100

        80 red balls and 60 blue balls to be moved from box A to Box B so that there are 80% of red balls in box A and 50% of blue balls in box B.

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

          Vanilla Cake:
          free willy:

          Box A has 200 red balls and 90 blue balls. Box B has 80 red balls and 100 blue balls. How many red balls and blue balls need to be moved from box A to Box B so that there are 80%of red balls in box A and 50% of blue balls in box B.

          Hi free willy,

          Your question is similar to RGPS P6 SA1 2009 P2 Q18 and the model solution had been provided by http://www.postimage.org/image.php?v=aVNZHuS on 22 Mar 2010.
          Tang had also provided his http://www.kiasuparents.com/kiasu/forum/viewtopic.php?t=280&postdays=0&postorder=asc&start=1170 on 19 Mar 2010.

          Using simultaneous equation to solve while waiting for Mathsguru's model solution.

          Final scenario
          Box A
          Red balls : Blue balls
          4 : 1 (80% : 20%)

          Box B
          Red balls : Blue balls
          1 : 1 (50% : 50%)

          4A+B = 200+80 = 280
          A+B = 90+100 = 190

          3A = 90
          A = 30
          B = 190-30=160

          Final scenario
          Box A
          Red balls : Blue balls
          120 : 30

          Box B
          Red balls : Blue balls
          160 : 160

          Before scenario
          Box A
          Red balls : Blue balls
          200 : 90

          Box B
          Red balls : Blue balls
          80 : 100

          80 red balls and 60 blue balls to be moved from box A to Box B so that there are 80% of red balls in box A and 50% of blue balls in box B.

          Hi Vanilla Cake,

          Don’t you think the statement, “there are 80% of red balls in box A ….” is different from “80% of balls in Box A are red …..”

          1 Reply Last reply Reply Quote 0
          • V Offline
            Vanilla Cake
            last edited by

            Dharma:
            Vanilla Cake:

            [quote=\"free willy\"]Box A has 200 red balls and 90 blue balls. Box B has 80 red balls and 100 blue balls. How many red balls and blue balls need to be moved from box A to Box B so that there are 80%of red balls in box A and 50% of blue balls in box B.

            Hi free willy,

            Your question is similar to RGPS P6 SA1 2009 P2 Q18 and the model solution had been provided by http://www.postimage.org/image.php?v=aVNZHuS on 22 Mar 2010.
            Tang had also provided his http://www.kiasuparents.com/kiasu/forum/viewtopic.php?t=280&postdays=0&postorder=asc&start=1170 on 19 Mar 2010.

            Using simultaneous equation to solve while waiting for Mathsguru's model solution.

            Final scenario
            Box A
            Red balls : Blue balls
            4 : 1 (80% : 20%)

            Box B
            Red balls : Blue balls
            1 : 1 (50% : 50%)

            4A+B = 200+80 = 280
            A+B = 90+100 = 190

            3A = 90
            A = 30
            B = 190-30=160

            Final scenario
            Box A
            Red balls : Blue balls
            120 : 30

            Box B
            Red balls : Blue balls
            160 : 160

            Before scenario
            Box A
            Red balls : Blue balls
            200 : 90

            Box B
            Red balls : Blue balls
            80 : 100

            80 red balls and 60 blue balls to be moved from box A to Box B so that there are 80% of red balls in box A and 50% of blue balls in box B.

            Hi Vanilla Cake,
            Don’t you think the statement, “there are 80% of red balls in box A ….” is different from “80% of balls in Box A are red …..” [/quote]Hi Dharma,
            Thanks for your remainder. 😄
            Something is not right in the way this question is phrased. 😢
            free willy:
            I don't know how to help my P6 boy with this homework question. He miss the class cause he had to go for tournment.
            Hi free willy,
            Pls clarify with your P6 boy about this homework question and let us know.
            Thanks.

            1 Reply Last reply Reply Quote 0
            • G Offline
              Guan Hui
              last edited by

              free willy:
              I don't know how to help my P6 boy with this homework question. He miss the class cause he had to go for tournment.


              Box A has 200 red balls and 90 blue balls. Box B has 80 red balls and 100 blue balls. How many red balls and blue balls need to be moved from box A to Box B so that there are 80%of red balls in box A and 50% of blue balls in box B.
              I think 80% of red balls mean 80 % of total red balls while 50 % of blue balls means 50% of total blue balls

              200+80=280 red balls
              80% of 280=224 red balls
              90+100=190 blue balls
              50% of 190=95 blue balls

              For me, from my interpretation 24 red balls and 5 blue balls need to be move from box B to A..
              I dunno if I am correct.>.< Just my opinion.
              (I know question say how many balls from BOX A to BOX B)

              1 Reply Last reply Reply Quote 0
              • S Offline
                shemum
                last edited by

                Hi Maths Guru,


                Please help me to solve the below question.

                An MRT train was 2/5 full of passengers. At the first station, 1/2 of the passengers alighted and 17 people boarded the train. The train is now 1/4 full. How many passengers were there on the train at first?

                Thank you.

                Shemum

                1 Reply Last reply Reply Quote 0
                • V Offline
                  verykiasu2010
                  last edited by

                  shemum:
                  Hi Maths Guru,


                  Please help me to solve the below question.

                  An MRT train was 2/5 full of passengers. At the first station, 1/2 of the passengers alighted and 17 people boarded the train. The train is now 1/4 full. How many passengers were there on the train at first?

                  Thank you.

                  Shemum
                  2/5 minus half = 1/5 = 0.2Full

                  0.2Full + 17 = 0.25F

                  hence 17 = 0.05Full

                  original number = 0.4Full = 8 x 0.05Full = 8x 17 = 136

                  should be easy with the model / diagram method too

                  1 Reply Last reply Reply Quote 0
                  • A Offline
                    adhdadhd
                    last edited by

                    shemum:
                    Hi Maths Guru,


                    An MRT train was 2/5 full of passengers. At the first station, 1/2 of the passengers alighted and 17 people boarded the train. The train is now 1/4 full. How many passengers were there on the train at first?
                    Let me try:

                    Say, full train has 20 units.
                    2/5 full = 8 units.
                    1/2 alighted ==> 4 units alighted and left with 4 units.
                    17 people boarded ==> 4 units (left over) + 17
                    1/4 full = 5 units.
                    Thus, 1 unit = 17 passengers.
                    So MRT was originally 8 units = 136 passengers

                    Correct me if I am wrong.

                    1 Reply Last reply Reply Quote 0
                    • A Offline
                      adhdadhd
                      last edited by

                      shemum:
                      Hi Maths Guru,


                      An MRT train was 2/5 full of passengers. At the first station, 1/2 of the passengers alighted and 17 people boarded the train. The train is now 1/4 full. How many passengers were there on the train at first?
                      Let me try:

                      Say, full train has 20 units.
                      2/5 full = 8 units.
                      1/2 alighted ==> 4 units alighted and left with 4 units.
                      17 people boarded ==> 4 units (left over) + 17
                      1/4 full = 5 units.
                      Thus, 1 unit = 17 passengers.
                      So MRT was originally 8 units = 136 passengers

                      Correct me if I am wrong.

                      1 Reply Last reply Reply Quote 0
                      • G Offline
                        Guan Hui
                        last edited by

                        Solve using Percentage is easier to see for me=)

                        2/5=40%
                        1/2 left so remain=20%
                        +17 people=25%
                        so 5%=17 people
                        40%=17x8
                        =136 people^^



                        Both is correct moderators merge this with mathsguru thread?

                        1 Reply Last reply Reply Quote 0

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