P6 Maths Qn

• Chocolate Cake

  12 Dec 08, 11:23

  Got this qn from another blog and so far nobody has answered since it was posted on 10 Dec 2008. Pls kindly spare your time & try to answer it.

  A 6-sided dice with equal chances has the numbers 1, 2, 3, 4. 5 and 6 written on its faces. The dice is tossed twice and the numbers obtained are recorded accordingly. What is the maximum number of ways for the sum of the two recorded numbers to be a number that has 2 factors only?

  BTW, this is my first posting in this forum & I find it helpful with many nice ppl around.

  Cheers.

  

   

   

   

• jayh272416

  12 Dec 08, 11:29

  possible answers are 2 3 4 5 6 7 8 9 10 11 12

  2 factos = prime number

  primes are 2 3 5 7 11

  so its 5 ways.

  *edit*

  unless you mean that, for example, 6 and 5, and 5 and 6 are different though the sum is the same,

  2 has one way (1 1)
  3 has 2 ways
  5 has 4 ways
  7 has 6 ways
  11 has 2 ways

  so it means it is 15 ways.

• Chocolate Cake

  13 Dec 08, 09:20

  Yes, got the reply from the person that had posted this qn. Answer is 15 ways. Thanks for your super fast & detailed explanation. Cheers.
• syncopation_music

  24 Jan 09, 23:07

  hi ..i need to understand how to explain the answer to a P6 student.so its easy to learn .its by a famous maths author..and no worked solution at all ...zzz

   

  hope anyone can help me with this ..answers i have to get the book then check

  all help deeply appreciated ;)

   

  Mr Lim bought a total of 75 apples and oranges.After 1/3 of the apples and
  3/4 of the oranges were eaten ,a total of 25 apples and oranges were left.
  How many apples did Mr Lim buy?

  Tap A can fill an empty tank in 15min.Tap B can empty a similar tank that
  is completely filled in 12 mins .Both taps are turned on at the same time when 3/4 of the tank is filled with water.How long will it take for the tank to be completely emptied ?

   

  

   

  [Please ignore the dimension of the tank ..no dimension is given in the REAL QUESTION ]

  this is just a generic pic of Tap A[top one] and Tap B[the draining tap]

  
  At a stall , there are some buns and cakes .If 20 buns and 60 cakes are sold per minute ,there will be 80 cakes left when all the buns are sold .
  If 60 buns and 20 cakes are sold per minute ,there will be 400 cakes left and when all the buns are sold.How many buns are there at stall ?

• jayh272416

  27 Jan 09, 21:31

  Originally posted by syncopation_music:

  Mr Lim bought a total of 75 apples and oranges.After 1/3 of the apples and
  3/4 of the oranges were eaten ,a total of 25 apples and oranges were left.
  How many apples did Mr Lim buy?

  
  use algebra

  A+O=75
  (2/3)A+(1/4)O=25
  therefore 8/3A+O=100
  5/3A=25
  number of apples = 25 x 3/5 = 15
  number of oranges = 75-15 = 60

• jayh272416

  27 Jan 09, 21:34

  Originally posted by syncopation_music:

  Tap A can fill an empty tank in 15min.Tap B can empty a similar tank that
  is completely filled in 12 mins .Both taps are turned on at the same time when 3/4 of the tank is filled with water.How long will it take for the tank to be completely emptied ?

   

  

   

  [Please ignore the dimension of the tank ..no dimension is given in the REAL QUESTION ]

  this is just a generic pic of Tap A[top one] and Tap B[the draining tap]

  
  Convert to 1 min

  in 1 min 1/15 of the tank is filled up and 1/12 of the tank is emptied

  therefore in 1 min, the change in volume is 1/15-1/12

  = 4/60-5/60
  = -1/60

  thus 1/60 of the tank is emptied in 1 min

  time taken to empty 3/4 of the tank is (3/4)/(1/60)

  = 45 min

• Daisuke-kun

  27 Jan 09, 21:35

  wah!

  pri6 learn dis liao?

  shocking

• jayh272416

  27 Jan 09, 21:38

  Originally posted by syncopation_music:

  At a stall , there are some buns and cakes .If 20 buns and 60 cakes are sold per minute ,there will be 80 cakes left when all the buns are sold .
  If 60 buns and 20 cakes are sold per minute ,there will be 400 cakes left and when all the buns are sold.How many buns are there at stall ?

  
  let m be the time taken to sell all the buns using scenario 1
  let n be the time taken to sell all the buns using scenario 2

  therefore
  20m = 60n
  60m+80=20n+400

  divide both equations by 20

  m=3n
  3m+4=n+20

  take 3 times of the first eqn

  3m = 9n
  sub into 2nd eqn
  9n+4=n+20
  8n=16
  n=2

  thus number of buns sold is 60n=120

• jayh272416

  27 Jan 09, 21:39

  Originally posted by Daisuke-kun:

  wah!

  pri6 learn dis liao?

  shocking

  
  pri 6 learn algebra woh.

• d3sT1nY

  28 Jan 09, 01:08

  I though primary school still using the bar model kind of thing. Can use algebra meh? Don't play cheat leh. Haha.

• SBS261P

  28 Jan 09, 02:33

  the bun one can have creative method of solving if i sell 20 bun and 60 cake per minute i will have 80 cake left this means that if i sell 60 bun and 180 cake per 3 minutes, i will have 80 cake left if i sell 60 bun and 20 cake per 1 minute, i will have 400 cake left. so for every 60 bun i sell, for the first one i sell 180 cake, second one i sell 20 cake the difference in cake i sell is 160 cake. i got 400 - 80 = 320 more cakes if i sell slower 320 / 160 = 2 means that i sell 2 sets of 60 bun = 120 bun i think this easier for primary school to learn? or maybe because i lao jiao so i think this one very simple but primary student think very hard? not sure
• syncopation_music

  18 Feb 09, 12:52

  hi this two question is tough .. i would need some help to explain to my student

   

  hope any kind soul help out there

   

  

  

• baiyun

  18 Feb 09, 15:14

   

  Hi

  Hope it helps.

  

• syncopation_music

  22 Feb 09, 22:50

  A cylindrical drum is being filled with petrol flowing from a tap. The volume of petrol in the drum ,V litres , after x minutes is given by V=20+4x litres .Find the volume of petrol in the drum after 38 minutes .

   

  when i look at the answer , i coudnt figure out the answer for this is 80 litres .

   

  any person who want to try ?

   

   

• d3sT1nY

  23 Feb 09, 09:20

  Originally posted by syncopation_music:

  A cylindrical drum is being filled with petrol flowing from a tap. The volume of petrol in the drum ,V litres , after x minutes is given by V=20+4x litres .Find the volume of petrol in the drum after 38 minutes .

   

  when i look at the answer , i coudnt figure out the answer for this is 80 litres .

   

  any person who want to try ?

  The answer sheet is wrong. 

• 787180

  23 Feb 09, 09:46

  How to do this in a simpler manner? Kit and Roy are given some money.If Kit and Roy spend $50 and $25 respectively each day,Kit will still have $600 when Roy has spent all his money.If Kit and Roy spend $25 and $50 respectively,Kit will still have $1800 when Roy has spent all his money.How much money is given to each boy?
• Only-Way-4-Destiny!

  23 Feb 09, 16:27

  All relax ok? Its just P6 maths qn

   

• Amktsy

  23 Feb 09, 16:41

  i think the answer is 11.

  not sure correct or not but i did pass my maths for psle although not really good.

• dlocenot

  23 Feb 09, 17:45

  K-2R=600

  K-0.5R=1800

  Solving, Kit=2200, Roy=800

• syncopation_music

  21 Mar 09, 11:27

  Hi all , just want to know where i gone wrong

  i have been trying but i just dont seems to get the answer which is $120

   

  The question as below :

   

  A clock costs five times as much as a lamp .If the lamp costs $80 less than the clock ,Find the total cost of the clock and the lamp

   

  much appreciated for any help

  thanks

   

   

• skythewood

  21 Mar 09, 11:47

  Originally posted by syncopation_music:

  Hi all , just want to know where i gone wrong

  i have been trying but i just dont seems to get the answer which is $120

  The question as below :

  A clock costs five times as much as a lamp .If the lamp costs $80 less than the clock ,Find the total cost of the clock and the lamp

  much appreciated for any help

  thanks

  .......

  i think helping students understand how to approach the question is as important as telling them what the answer is. That is especially important for teaching primary school kids. And i think this question is very very very basic.

  step 1: draw it out

  lamp ===>  |     |
  clock ===>  |     |      |       |      |        |

  reason, show that clock is 5 times more expensive.

  step 2, reasoning.   4 units is $80. make sense?

  step 3, maths          1 unit is $20

  step 4, maths           5 units, the clock is $100

  step 5, maths            total is $120

   

  teach the approach, please....

• syncopation_music

  22 Mar 09, 18:24

  Originally posted by skythewood:

  .......

  i think helping students understand how to approach the question is as important as telling them what the answer is. That is especially important for teaching primary school kids. And i think this question is very very very basic.

  step 1: draw it out

  lamp ===>  |     |
  clock ===>  |     |      |       |      |        |

  reason, show that clock is 5 times more expensive.

  step 2, reasoning.   4 units is $80. make sense?

  step 3, maths          1 unit is $20

  step 4, maths           5 units, the clock is $100

  step 5, maths            total is $120

   

  teach the approach, please....

  thank you for helping

  anyway i have to admit sometimes i am stuck at question and doesnt have to make noise over some stuck up ..

  sometimes i just too bothered with alot of math model question which is difficult but overlooking the simple ones on my part 

   

• syncopation_music

  22 Mar 09, 18:27

  hmmm , i still not sure how to solve this .. so far no answer to this

   

  would appreciate if any kind soul can help :)

  

• wee_ws

  22 Mar 09, 19:38

  Hi,

    From the question, we obtain

    3 units -> 8 pens,

    2 units + $1 -> 6 pens.

    Since 3 units -> 8 pens, 9/4 units -> 6 pens equivalently.

    So, 2 units + $1 is equivalent to 9/4 units.

    Try to continue from this point onwards.  Thanks!

  Cheers,
  Wen Shih

• skythewood

  22 Mar 09, 19:52

  Originally posted by syncopation_music:

  hmmm , i still not sure how to solve this .. so far no answer to this

   

  would appreciate if any kind soul can help :)

  

  can you please teach the approach? questions will always vary, and by teaching the approach, you will be able to answer all similar questions. not much point in posting 300  answer to 300 questions, when just one model of approach will do. the approach, please the approach.

  step 1: draw it out

  8 pens ===>  | 1  |   2 |  3   | 
  6 pens ===>  | 1  |   2 |                  and          $1                  

  reason, show that cost of pens

  step 2, reasoning.   3 pens cost  (3/2) unit. make sense?

  step 3, reasoning.   3 pens cost 1 unit and (1/2) of a dollar.

  step 4, maths         ...........................