Help pls... pri. 6 maths question i cant solve

• pongchak

  15 May 08, 00:34

  i give tuition then end up these 2 questions i cant do at all. so can u help me pls guys?
  
  btw, pls tell me how to solve without using algreba or equation since its supposed to be p6 work. thanks
  
  q1 -
  
  there r 60 shirts n pants in a store. each shirt cost $9 n pants $7. if the total cost of the shirts is $188 more than the total cost of the pants, how many shirts r there in the store?
  
  q2 -
  
  the number of grey marbles to black marbles is ratio 4:5. later, 8 grey marbles were taken out n 20 black marbles were added in. after that, the ration of grey to black marbles is 4:11.
  how many marbles of each color were there in the end?

• rain-coat

  15 May 08, 10:30

  qn1

  9x-7(60-x)=188?

  16x+420=188

  16x=602

  x=38

  60-38=22

  38-22=16

  therefore there are 16 more shirts

• eagle

  15 May 08, 10:38

  Q1

  Without using algebra... I would do this in pri sch

  30*9 - 30*7 = 60 => so need more shirts
  35*9 - 25*7 = 126 => so need more shirts
  40*9 - 20*7 = 220 => so need less shirts
  38*9 - 22*7 = 188

  So there are 38 shirts and 22 pants in the store

   

• rain-coat

  15 May 08, 10:39

  aiya now pri sch diff already..who knows they may even teach trigo in p sch next time

• BenBenDeZhu

  15 May 08, 10:39

  wah liew so different from my time like over 12 years ago

• cuddles

  15 May 08, 10:53

  actually we used to draw those bar diagrams and divide it into the number of parts in order to see the difference.. and we did do such questions before, just that like rain coat, we learnt algebra/equation and all those.. so it's kind of hard for us to revert to how we used to do it in primary..

• eagle

  15 May 08, 10:56

  actually pri sch also considered as algebra... just that we use bar charts... Then we use 4 units instead of 4x

• the Bear

  15 May 08, 11:02

  these questions are designed to find the next Euler or Euclid in Singapore...

  or to stress the hell out of children and parents who believe their children must be able to do these questions...

• eagle

  15 May 08, 11:16

  Originally posted by the Bear:

  these questions are designed to find the next Euler or Euclid in Singapore...

  or to stress the hell out of children and parents who believe their children must be able to do these questions...

  they definitely can do one

  Just how long they take

  Trial and error can solve a lot of pri sch questions de

• SBS n SMRT

  17 May 08, 22:50

  Originally posted by pongchak:

  i give tuition then end up these 2 questions i cant do at all. so can u help me pls guys?
  
  btw, pls tell me how to solve without using algreba or equation since its supposed to be p6 work. thanks
  
  q1 -
  
  there r 60 shirts n pants in a store. each shirt cost $9 n pants $7. if the total cost of the shirts is $188 more than the total cost of the pants, how many shirts r there in the store?
  
  q2 -
  
  the number of grey marbles to black marbles is ratio 4:5. later, 8 grey marbles were taken out n 20 black marbles were added in. after that, the ration of grey to black marbles is 4:11.
  how many marbles of each color were there in the end?

  q2: maybe can use simulanteous equations

• secretliker

  17 May 08, 23:15

  Q2

  Gray:Black = 4:5

  Since 8 Grey marbles were taken out, the unsimplified ratio of Gray:Black must be more than or 2 times that of 4:5

  Use Guess & Check.

  12:15 becomes 4:35

  16:20 becomes 8:40 = 1:5

  20:25 becomes 12:45 = 4:15

  24:30 becomes 16:50 = 8:25

  28:35 becomes 20:55 = 4:11

  So in the end, 20 Gray, 55 Black.

  By algebra,

  4x - 8 / 5x + 20 = 4/11

  x=7

  In the end

  Gray: 4(7)-8 = 20

  Black: 5(7) + 20 = 55

• seotiblizzard

  17 May 08, 23:37

  Woah maths. My most hated subj. Zzz.

• deathmaster

  1 Jun 08, 12:52

  also face the same problem with my sis. any other primary sch-accepted methods other than guess and check?

  why do primary sch teachers not allow algebra to be use? the teachers minus marks from those using algebra, even though they got the correct answer.

  also, when they progress to sec 1, they won't be allowed to use guess and check anymore wad, and have to use algebra to solve qsn. wouldn't it make more sense to allow them to use algebra?

   

   

• secretliker

  3 Jun 08, 22:59

  Originally posted by deathmaster:

   

  why do primary sch teachers not allow algebra to be use? the teachers minus marks from those using algebra, even though they got the correct answer.

  also, when they progress to sec 1, they won't be allowed to use guess and check anymore wad, and have to use algebra to solve qsn. wouldn't it make more sense to allow them to use algebra?

  
  Unless the question specifically state don't use algebra. Otherwise, any correct method should be fine.

• Someone7

  11 Jun 08, 22:40

  This is a method using model. The easier way for students in Primary school to understand. I hope my reply is not too late. I really hope you would understand the model.

  

  Firstly, since 8 is able to be divided by the 4 units, we wil do exactly that. Since the units are equal for both the grey and black marbles, we can also do the same for the units representing the black marbles.

  Secondly, we will now look at the black marbles. since we can see that apart from the 5 original units, we still need 6 more units, since there are 11 units altogether in the end, we can draw 6 more unit, the size of (an original unit-2). Now, you must wonder where does this 6 units come from. Firstly, they come from the 20 marbles that are added in. But that is not all, there is also the 10 extra ones that we took out from the original unit. Thus, we can say that the 6 units is equals to 20+10. From there, i'm sure that you can work out the answer yourself.

  My answer is: Blue-20marbles, Black-55 marbles.

  I hope my answer is correct and i hope that it has helped you! This method can be used if any of the before and after ratio is the same; like this question.

   

   

   

   

   

• SBS 9613Z

  14 Jun 08, 22:13

  Originally posted by deathmaster:

  also face the same problem with my sis. any other primary sch-accepted methods other than guess and check?

  why do primary sch teachers not allow algebra to be use? the teachers minus marks from those using algebra, even though they got the correct answer.

  also, when they progress to sec 1, they won't be allowed to use guess and check anymore wad, and have to use algebra to solve qsn. wouldn't it make more sense to allow them to use algebra?

   

   

  Algebra can be used in pri sch; MOE said that it's perfectly fine and that marks would not be deducted in the PSLE. I used it in the PSLE without any problem.      (:

• popikachu

  15 Jun 08, 21:59

  hmm nope this is what i get 5 years ago too ^^

• MrSean

  20 Jun 08, 04:41

  Originally posted by SBS 9613Z:

  Algebra can be used in pri sch; MOE said that it's perfectly fine and that marks would not be deducted in the PSLE. I used it in the PSLE without any problem.      (:

  
  You are absolutely right.

  Problem with math is that when you go to secondary school, almost all you have learnt in primary school becomes useless. Primary school is about creative solving (when you get to P5-6 standard) and Secondary school is more focused on application of formulae etc.

  Trust me you need to be able to do these to do well at PSLE. I still remember, I would scratch my head out for an entire day trying to solve a question if I had to. Do that, in the end you will benefit. Sometimes I fall asleep before I can solve it, but often that helps too because your mind is active when you are asleep. Then when I wake up BANG I know the answer.

• gunner77

  21 Jun 08, 02:23

  nowadays pri 6 math owned me.

• Maith

  22 Jun 08, 04:07

  Originally posted by gunner77:

  nowadays pri 6 math owned me.