Pr 6 maths Problem sum

• Lxlim

  28 May 10, 13:02

  • Hello bro and sis

   

  Please help me with the problem as I am unable to solve.

   

  1.Paul's height is 2/5 of his father's height and 3/4 of Sean's height.

  (a)Fingthe ratio of paul's height to the total height of his father and Sean.

  (b)If Sean is 84cm shorter than Paul'sfather,find Paul's height in metres.

   

  2.Mr Jones spent $990 on a DVD player and 55% of the remainder on a sofa set.He left with 30% of his original amount of money.Find the amount of money he had at first.

   

   

  Thanks for your help.

  LX

   

   

   

• dylanninetytwo

  28 May 10, 13:33

  My ans is:

  1a) 6:23

  1b) 0.72m

   

  2)  $2970

  You let the amount he have at first be x.

  So,  X - 990 - 0.55( X-990) = 0.3X

  X= ANS

• wee_ws

  28 May 10, 13:55

  Hi,

    For primary level, students are taught to apply the model method. Thanks.

  Cheers,
  Wen Shih

• Lxlim

  28 May 10, 13:57

  Thanks,Dy

  

• Lxlim

  28 May 10, 14:20

  Originally posted by wee_ws:

  Hi,

    For primary level, students are taught to apply the model method. Thanks.

  Cheers,
  Wen Shih

   

   

  Ths for your help!

   

• Dragonaxe

  28 May 10, 14:58

  Originally posted by Lxlim:

  • Hello bro and sis

   

  Please help me with the problem as I am unable to solve.

   

  1.Paul's height is 2/5 of his father's height and 3/4 of Sean's height.

  (a)Fingthe ratio of paul's height to the total height of his father and Sean.

  (b)If Sean is 84cm shorter than Paul'sfather,find Paul's height in metres.

   

  2.Mr Jones spent $990 on a DVD player and 55% of the remainder on a sofa set.He left with 30% of his original amount of money.Find the amount of money he had at first.

   

   

  Thanks for your help.

  LX

  1)

  RANDOM NUMBER -> 6 

  PAUL's HEIGHT -> 6u

  PAUL's FATHER -> 5/2 x 6 = 5(6/2) = 15

  SEAN -> 4/3 x 6 = 4(6/3) = 8

  15+8 = 23

  ANSWER(a) : 6:23

  7u ->84

  6u -> 6/7 x 84cm = 6(84/7) = 6 x 12 = 72cm = 0.72m

  ANSWER(b) : 0.72m

   

  2)

  45%(REMAINDER) -> 30% total

  5%(REMAINDER) -> 1/9 x 30 = 3.33%

  10%(REMAINDER) -> 6.66%  = 2/3

  50%(REMAINDER) -> 2/3 x 5/1 = 10/3 = 3 1/3 % = 33.33333% = 1/3

  100%(REMAINDER) -> 1/3 x 2 = 2/3

  1/3 -> $990

  3/3 -> $990 x 3 = ($1000x3) - 3($1000-$990) = $3000 - $30 = $2970

  ANSWER : $2970

   

  P6 Maths Olympiad student here. Pretty easy i guess.

• ~PEPPER~

  28 May 10, 15:53

  Originally posted by wee_ws:

  Hi,

    For primary level, students are taught to apply the model method. Thanks.

  Cheers,
  Wen Shih

  
  PSLE cant use algebra?

• Dragonaxe

  28 May 10, 15:58

  Originally posted by ~PEPPER~:

  
  PSLE cant use algebra?

  P6 Algebra Maths TB only teach you the basics.

  Like

  y x 4 = 4y 

  then 

  4y + 3 - 2y + 4

  = 4y - 2y + 7

  = 2y + 7

   

• -StarDust-

  28 May 10, 16:01

  Lastime sec school then teach algebra syllabus changed nowadays.

• Genie99a

  28 May 10, 16:37

  I feel embaressed... I didn't noe the answer lol..... epic fail

  Kind Regards

  Genie

• Lxlim

  28 May 10, 17:45

  Originally posted by dylanninetytwo:

  My ans is:

  1a) 6:23

  1b) 0.72m

   

  2)  $2970

  You let the amount he have at first be x.

  So,  X - 990 - 0.55( X-990) = 0.3X

  X= ANS

   

   

   

  I do not understand.Can u pls explain again?

   

• Jenia

  28 May 10, 18:41

  damn i cant do also, embarrassed sia. i dont understand this,

  1)

  RANDOM NUMBER -> 6 

  PAUL's HEIGHT -> 6u

  PAUL's FATHER -> 5/2 x 6 = 5(6/2) = 15

  can anyhow take random number 6 one meh ?

  no wonder i got a C for psle maths.

• wee_ws

  28 May 10, 20:15

  Hi,

    Let P represent Paul's height, F represent father's height, and S represent Sean's height.

    Given: F/P = 5/2 and S/P = 4/3.

    Consider the ratio (F + S)/P = F/P + S/P = 5/2 + 4/3 = 23/6.

    Now P : F + S = 6 : 23.

    Thanks.

  Cheers,
  Wen Shih

• Dragonaxe

  28 May 10, 20:16

  Originally posted by Jenia:

  damn i cant do also, embarrassed sia. i dont understand this,

  1)

  RANDOM NUMBER -> 6 

  PAUL's HEIGHT -> 6u

  PAUL's FATHER -> 5/2 x 6 = 5(6/2) = 15

  can anyhow take random number 6 one meh ?

  no wonder i got a C for psle maths.

  6 is divisible by 2 and 3.

• -StarDust-

  28 May 10, 20:31

  P6 problem also so hard.

• wee_ws

  28 May 10, 20:42

  Hi,

    Indeed, a lot is expected of our students.

    The following are suggested thinking skills and heuristics for problem solving listed in the primary and lower secondary mathematics syllabuses.

  Thinking Skills
  Classifying
  Comparing
  Sequencing
  Analysing parts and whole
  Identifying patterns and relationships
  Induction
  Deduction
  Generalising
  Verifying
  Spatial visualisation

  Heuristics for Problem Solving
  Act it out
  Use a diagram/model
  Make a systematic list
  Look for patterns
  Work backwards
  Use before-after concept
  Use guess and check
  Make suppositions
  Restate the problem in another way
  Simplify the problem
  Solve part of the problem
  Thinking of a related problem
  Use equations

    Source: p12, The Singapore Model Method for Learning Mathematics.

    Parents and students should read further for details. Thanks.

  Cheers,
  Wen Shih

• Dragonaxe

  29 May 10, 17:52

  2357 x 62 = 2357 x 31 x 2 

  = (2000x31+300x31+50x31+7x31) x 2

  = (60000+2000+9000+300+(500x3+50)+210+7) x2

  = (62000+9300+1550+217) x2

  = (70000+1300+1550+217) x2

  = 2(71300+1550+217)

  = 2(72500+550+17)

  = 2(72500+567)

  = 2(72500+500+60+7)

  = 2(73000+60+7)

  = 2(73067)

  = 2 x 73067

  = 70000x2+3000x2+60x2+7x2

  = 140 000+6 000+120+14

  = 146 000+134

  = 146 134

   

  3985 x 96 = 3985 x 48 x 2

  = 3985 x 24 x 2 x 2

  = 3985 x 12 x 2 x 2 x 2

  = 3985 x 6 x 2 x 2 x 2 x 2

  = 3985 x 3 x 2 x 2 x 2 x 2 x 2

  = (3000x3+900x3+80x3+5x3) x 2 x 2 x 2 x 2 x 2

  = (9000+2700+240+15) x 2 x 2 x 2 x 2 x 2

  = (11700 + 255) x 2 x 2 x 2 x 2 x 2

  = 11955 x 2 x 2 x 2 x 2 x 2

  = (11 000x 2+900x2+50x2+5x2) x 2 x 2 x 2 x 2

  = (22 000+1800+100+10) x 2 x 2 x 2 x 2

  = (23800+110) x 2 x 2 x 2 x 2

  = 23910 x 2 x 2 x 2 x 2

  = (23 000x2+900x2+10x2) x 2 x 2 x 2

  = (46000+1800+20) x 2 x 2 x 2 

  = 47820 x 2 x 2 x 2

  = (40000x2+7000x2+800x2+20x2) x 2 x 2

  = (80000+14000+1600+40) x 2 x 2

  = (94000+1640) x 2 x 2

  = 95 640 x 2 x 2

  = (95000x2+600x2+40x2) x 2

  = (190 000+1200+80) x 2

  = 191 280 x 2

  = 100 000x2+90 000x2+1 000x2+200x2+80x2

  = 200 000+180 000+2000+400+160

  = 380 000+2560

  = 382 560 

   

• ~PEPPER~

  29 May 10, 17:54

  Originally posted by Dragonaxe:

  2357 x 62 = 2357 x 31 x 2 

  = (2000x31+300x31+50x31+7x31) x 2

  = (60000+2000+9000+300+(500x3+50)+210+7) x2

  = (62000+9300+1550+217) x2

  = (70000+1300+1550+217) x2

  = 2(71300+1550+217)

  = 2(72500+550+17)

  = 2(72500+567)

  = 2(72500+500+60+7)

  = 2(73000+60+7)

  = 2(73067)

  = 2 x 73067

  = 70000x2+3000x2+60x2+7x2

  = 140 000+6 000+120+14

  = 146 000+134

  = 146 134

   

  3985 x 96 = 3985 x 48 x 2

  = 3985 x 24 x 2 x 2

  = 3985 x 12 x 2 x 2 x 2

  = 3985 x 6 x 2 x 2 x 2 x 2

  = 3985 x 3 x 2 x 2 x 2 x 2 x 2

  = (3000x3+900x3+80x3+5x3) x 2 x 2 x 2 x 2 x 2

  = (9000+2700+240+15) x 2 x 2 x 2 x 2 x 2

  = (11700 + 255) x 2 x 2 x 2 x 2 x 2

  = 11955 x 2 x 2 x 2 x 2 x 2

  = (11 000x 2+900x2+50x2+5x2) x 2 x 2 x 2 x 2

  = (22 000+1800+100+10) x 2 x 2 x 2 x 2

  = (23800+110) x 2 x 2 x 2 x 2

  = 23910 x 2 x 2 x 2 x 2

  = (23 000x2+900x2+10x2) x 2 x 2 x 2

  = (46000+1800+20) x 2 x 2 x 2 

  = 47820 x 2 x 2 x 2

  = (40000x2+7000x2+800x2+20x2) x 2 x 2

  = (80000+14000+1600+40) x 2 x 2

  = (94000+1640) x 2 x 2

  = 95 640 x 2 x 2

  = (95000x2+600x2+40x2) x 2

  = (190 000+1200+80) x 2

  = 191 280 x 2

  = 100 000x2+90 000x2+1 000x2+200x2+80x2

  = 200 000+180 000+2000+400+160

  = 380 000+2560

  = 382 560 

   

  wah

• Seowlah

  29 May 10, 20:26

  Originally posted by Dragonaxe:

  2357 x 62 = 2357 x 31 x 2 

  = (2000x31+300x31+50x31+7x31) x 2

  = (60000+2000+9000+300+(500x3+50)+210+7) x2

  = (62000+9300+1550+217) x2

  = (70000+1300+1550+217) x2

  = 2(71300+1550+217)

  = 2(72500+550+17)

  = 2(72500+567)

  = 2(72500+500+60+7)

  = 2(73000+60+7)

  = 2(73067)

  = 2 x 73067

  = 70000x2+3000x2+60x2+7x2

  = 140 000+6 000+120+14

  = 146 000+134

  = 146 134

   

  3985 x 96 = 3985 x 48 x 2

  = 3985 x 24 x 2 x 2

  = 3985 x 12 x 2 x 2 x 2

  = 3985 x 6 x 2 x 2 x 2 x 2

  = 3985 x 3 x 2 x 2 x 2 x 2 x 2

  = (3000x3+900x3+80x3+5x3) x 2 x 2 x 2 x 2 x 2

  = (9000+2700+240+15) x 2 x 2 x 2 x 2 x 2

  = (11700 + 255) x 2 x 2 x 2 x 2 x 2

  = 11955 x 2 x 2 x 2 x 2 x 2

  = (11 000x 2+900x2+50x2+5x2) x 2 x 2 x 2 x 2

  = (22 000+1800+100+10) x 2 x 2 x 2 x 2

  = (23800+110) x 2 x 2 x 2 x 2

  = 23910 x 2 x 2 x 2 x 2

  = (23 000x2+900x2+10x2) x 2 x 2 x 2

  = (46000+1800+20) x 2 x 2 x 2 

  = 47820 x 2 x 2 x 2

  = (40000x2+7000x2+800x2+20x2) x 2 x 2

  = (80000+14000+1600+40) x 2 x 2

  = (94000+1640) x 2 x 2

  = 95 640 x 2 x 2

  = (95000x2+600x2+40x2) x 2

  = (190 000+1200+80) x 2

  = 191 280 x 2

  = 100 000x2+90 000x2+1 000x2+200x2+80x2

  = 200 000+180 000+2000+400+160

  = 380 000+2560

  = 382 560 

   

  
  Don't confuse the PSLE maths students leh.

  By the way, PSLE maths students will solve Q1(a) by making the numerators to be the same hor ie 2/5 = 6/15 and 3/4 = 6/8 and the  ratio of paul's height to the total height of his father and Sean = 6 : 15 + 8 = 6 : 23. This type of question is commonly asked in PSLE maths and this method is found in many of the PSLE maths assessment guidebooks lor.

  For question 2, PSLE maths students do not learn expansion and solve for x lah.

  It can be solved by using the bar model lah.

  l                 70% of original                 l 30% of original  l

  l $990 - DVD Player l 55% of R - sofa l 45% of R - left   l