Q&A - PSLE Math

[rocklee]

Thanks PapayaDad for directing me to Tianzhu’s blog. Tianzhu’s blog has been really helpful.


A big thank you to Tianzhu for your time in looking up the slides.

How nice if all these different methods of solving problem sums are included in the textbooks and properly taught by school teachers, then we parents can save the time in sourcing for solutions and teaching kids ourselves!

[Musicstar]

Hi,


Someone can help to explain the answer provided. How to get 1 part of mangoes + 2 parts of durians = 4 x 164? I cannot figure it out.

Questions : Alan had a total of 448 mangoes and durians. He sold 1/4 of the mangoes and 1/2 of the durians. he sold 164 fruits altogether. How many mangoes and durians were sold respectively?

Answer :
1/4 part of mangoes + 1/2 part of durians = 164
1 part of mangoes + 2 parts of durians = 4 x 164 = 656
1 part of mangoes + 1 part of durians = 448
1 part of durians = 656 - 448 = 208
1/2 part of durians = 1/2 x 208 = 104
164-104 = 60
Alan sold 60 mangoes and 104 durians

[PapayaDad]

0.25m + 0.5d = 164

multiply everything by 4
1m+2d=4x164

[MathIzzzFun]

Musicstar:

Hi,


Someone can help to explain the answer provided. How to get 1 part of mangoes + 2 parts of durians = 4 x 164? I cannot figure it out.

Questions : Alan had a total of 448 mangoes and durians. He sold 1/4 of the mangoes and 1/2 of the durians. he sold 164 fruits altogether. How many mangoes and durians were sold respectively?

Answer :
1/4 total number of mangoes + 1/2 total number of durians = 164
multiply by 4 --> total number of mangoes + 2 x total number of durians = 4 x 164 = 656

Given --> Total number of mangoes + Total number of durians = 448
Total number of durians = 656 - 448 = 208
Durians sold --> 1/2 total number of durians = 1/2 x 208 = 104
Mangoes sold --> 164-104 = 60
Alan sold 60 mangoes and 104 durians

[Chalupa]

Hi I need a help to solve this problem.Three girls Alice,Bernica and carol shared a box of cubes in the ratio 5:3:4 and there 4 cubes left over.These 4 cubes were placed together with a second box of cubes.The second box contains 7/8 of the number of cubes in the first box.The girls then shared the cubes in the second box in the same ratio as before and there was no remainder.Find a) the total number of cubes they shared in the first box. B) the total number of cubes carol received after both rounds of sharing.

[MathIzzzFun]

rocklee:

Thanks PapayaDad for directing me to Tianzhu's blog. Tianzhu's blog has been really helpful.


A big thank you to Tianzhu for your time in looking up the slides.

How nice if all these different methods of solving problem sums are included in the textbooks and properly taught by school teachers, then we parents can save the time in sourcing for solutions and teaching kids ourselves!

you can take a look at some of the two ratios/double IF questions here :

http://www.flickr.com/photos/mathizzzfun/sets/72157632928079102/

http://www.flickr.com/photos/mathizzzfun/sets/72157632037121311/

cheers.

[Oldschool]

Chalupa:

Hi I need a help to solve this problem.Three girls Alice,Bernica and carol shared a box of cubes in the ratio 5:3:4 and there 4 cubes left over.These 4 cubes were placed together with a second box of cubes.The second box contains 7/8 of the number of cubes in the first box.The girls then shared the cubes in the second box in the same ratio as before and there was no remainder.Find a) the total number of cubes they shared in the first box. B) the total number of cubes carol received after both rounds of sharing.

Hi,

There is a similar question, which you may want to take a look first.

http://www.kiasuparents.com/kiasu/forum/viewtopic.php?p=973039#p973039


By the way, there is also a dedicated thread for Q&A PSLE Maths.

http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=69&t=280&start=8940

Regards

[rocklee]

Thanks MathIzzzfun. So it is back to school for me again. Need time to digest.

[tianzhu]

Hi


Questions involving Common Difference.

I wish to add on to my earlier reply to Musicstar’s question on Age Question.

Questions on Common Difference are a regular feature in past years papers. Different term such as Unchanged Difference or Difference Unchanged is also being used.

They can be solved by using MD, UM or UP.Usually, MD is used by the P3/P4 students.

I’ve compiled a list of questions on CD asked by members in KSP forum.
I’ve picked some of them and try to add some pictorials as shown in the slides below.

Generally, they can be grouped as follows:

A) Questions on difference in age.

B) Questions involving two persons receiving an equal amount of money or other objects from another party.

C) Two persons giving away an equal amount of money or other objects to another party.

D) The same number of male/ female spectators leaving a football stadium.

E) Selling/buying an equal number of flowers.

(B) to (E) fall into the same category as transfer to/from two variables.

Football fans imagine, singing Ole, Ole, Ole, in Old Trafford Stadium.

Questions involving Common Difference (KSP).

1) Leon is 45 years older than Peter, in another 2 years times, Leon will be 6 times as old as Peter. How old is Leon now? (52)

2) At present, Ronald is 3 times as old as his sister. In 22 years' time, Ronald's age will be 19 years less than twice his sister's age. How old is Ronald now?(9)

3) The ratio of John's age to his uncle's age is 1:4. In 30 years' time, the ratio will become 2:3. How old is John now? (6)

4) When Mrs. Lee was 40 years old, her son was twice her daughter's age. Mrs Lee will be twice her son's age when her daughter is 28 years old. How old will Mrs Lee be when her daughter is 20 years old? (56 years old)

5) A florist had 84 stalks of orchids and 4 times as many stalks of roses in her shop. After buying an equal number of orchids and roses the ratio of the number of orchids to the number of roses became 5:9.How many stalks of orchids and roses did she buy altogether?( 462)

6) The salary of Mr. Lim and Mr. Tan was in the ratio 3:5. After they gave away an equal amount of $3500 to their wives, the ratio became 1:4. What was Mr. Lim's salary? (4500)

7) A fruit seller had a total of 204 red and green apples in the ratio of 9:8.
After he sold an equal number of each type of apple, the number of red and green apples left was in the ratio of 9:5. How many apples did he sell altogether? (162)

Frank has 2/5 as many blue as red marbles. After buying another 42 blue and 42 red marbles, Frank then had 5/9 as many blue marbles as red marbles. How many marbles did Frank have at first? (168)

9) Father gave Gary $570 and his sister $250. After their mother has
given them an equal amount, Gary’s amount was twice as much as his
sister’s. How much money did their mother give to each of them? (70)

10) Osman had $41 and Mike had $15. After each boy had bought the same textbook each at the bookshop, Osman had 5 times as much money as Mike. How much did the textbook cost? (8.50)

11) In a soccer stadium, the number of female to male spectators is 3:7. After 287 female and 287 male left the stadium, the ratio of female to male spectators became 2:5. How many spectators were there at first? (8610)

12) Dawei has $180 and Yawen has $55. After their aunt gave each of them an equal amount of money, Dawei had twice as much money as Yawen. How much money did their aunt give to each of them? (70)

Best wishes

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http://farm9.staticflickr.com/8099/8643979231_9abe6df1e0_z.jpg\">

[Musicstar]

Hi,


Can someone help to explain the following questions? Although my girl is already P6 but I have been doing this type of questions but still do not understand when to "+" and "-". How do I look at the question to understand? Can someone enlighten me to better understanding? My girl has this question wrong. I think she also still not sure how to do it. Sorry, it may be an easy question for others. Thank you for helping to explain.

Questions: Vicky and her sister have a sum of money . If Vicky gives $120 to her sister, she will have 3 times as much money as her sister. If Vicky gives an additional $40 to her sister, she will have $240 more than her sister . How much money does her sister have?

Answer : 2u = 40 +240+40 = $320
1 u = 160
160 - 120 =40
Her sister has $40.