Q&A - PSLE Math

[Dharma]

tianzhu:

Hi


Another interesting question from onsponge, students who are more mathematically inclined often solve such questions using simultaneously equations as they are two unknowns and two equations.

For the benefits of future PSLE students,how about coming up with some strategies(heuristics taught in primary schools) to teach students cope with such questions?

Let us make this a uniquely KSP experience, active participation from members is strongly encouraged.

There were 32 tourists on a bus. 2/5 of the men and 1/4 of the women were from Singapore. The total number of tourists who came from Singapore was 11. How many men came from Singapore?( P6 Nan Hua CA1 2010 P2 Q11)

Best wishes

Hi Tianzhu,

http://postimage.org/image/2hakmanl0/

[tianzhu]

Hi Dharma


Thank you.

Best wishes

[P5G]

Please help.


24)

1/8 of a jug of lemonade was syrup. 1/4 of it was ice and the remaining was water. What was the ratio of the amount of water to the amount of syrup used to make the lemonade?

Answer given in worksheet is 5 : 1.


TIA

[P5G]

Please help.


Q24)

1/8 of a jug of lemonade was syrup. 1/4 of it was ice and the remaining was water. What was the ratio of the amount of water to the amount of syrup used to make the lemonade?


Answer given in the worksheet is 5 : 1.


TIA.

[tianzhu]

P5G:

1/8 of a jug of lemonade was syrup. 1/4 of it was ice and the remaining was water. What was the ratio of the amount of water to the amount of syrup used to make the lemonade?

Answer given in worksheet is 5 : 1.

Hi P5G

Draw a rectangular block and divide it into 8 units.

1 unit ----- syrup
2 units ----- ice (represents ¼ of jug)
5 units ----- water(remainder)

water:syrup ----- 5:1

Best wishes

[tianzhu]

Hi P5G


Please refer to your earlier post.
http://www.kiasuparents.com/kiasu/forum/viewtopic.php?t=17268

Best wishes

[Muffins]

P5G:

Please help.


Q24)

1/8 of a jug of lemonade was syrup. 1/4 of it was ice and the remaining was water. What was the ratio of the amount of water to the amount of syrup used to make the lemonade?


Answer given in the worksheet is 5 : 1.


TIA.

1/4 = 2/8
2/8 + 1/8 = 3/8 (Syrup + Ice)
8/8 - 3/8 = 5/8 (Water)
5/8 : 1/8 = 5:1

Hope I helped!

P.S. Anyway, the ratio would change soon, as the ice would have melted :lol: :rotflmao:

[Brenda10]

tianzhu:

Hi


Some interesting questions from onsponge.

2)If Ahmad gives Pillay 17 marbles, the ratio of his marbles to that of Pillay's will be 4:7. If Ahmad gives Pillay 5 marbles, both will have the same number of marbles. How many marbles does Ahmad have? ( Singapore Chinese Girls' School P6 2010 SA1 Maths Q10)

Best wishes

Hi Tianzhu

DD working

A : P
4 : 7 (End) } 8 : 14
+17 -17 (Changes) } +17 -17
? : ? (Before) } ? : ?

A : P
1 : 1 (End) } 11 : 11
+5 -5 (Changes) } + 5 : -5
? : ? (Before) } ? : ?

11 - 8 = 3
17 - 5 = 12
12 / 3 = 4

Therefore 8 x 4 + 17 = 49

Thank you.

[Brenda10]

tianzhu:

Hi


Some interesting questions from onsponge.
3)Ben and Marcus received some money from their mother. Marcus would have $64 more than Ben if Ben gave 2/5 of his share to Marcus. Marcus would have $144 more than Ben if Ben gave 2/3 of his share to Marcus. How much money did Ben receive from his mother? (Singapore Chinese Girls' School P6 2010 SA1 Maths Q13)

Best wishes

Hi Tianzhu

DD working:

3/5 = 6/15
2/3 = 10/15

10- 6= 4
144 - 64 = 80
80 / 4 = 20
15 x 20 = 300*

*This answer is different with the answer key: 150

We then checked the onsponge forum and realize that instead of 10 - 6 =4 , it should be 10 + 10 = 20, 6 + 6 = 12** and resulted 20 - 12 = 8

As such, it will become :
80/ 8 = 10
15 * 10 = 150

**DD cannot understand this particular step and appreciate your kind help.

Thank you

[tianzhu]

Hi Brenda10


It’s good to draw a model for this question.

You have a good start; you’ve worked out the common multiple for 3 and 5 which is 15.

To begin, Ben has 15 units.

In the first case, Ben gave 6 units to Marcus,leaving a remainder of 9 units.

In the second case, Ben gave 10 units to Marcus, leaving a remainder of 5 units.

The difference between the first and second case is 8 units(take away 4 units for Ben and add 4 units to Marcus) and their difference is 80.
This gives 1 unit equal to 10.

I remember drawing out the MD for a similar type of question some months ago; I’ll try to find it. If I can’t find it, I’ll draw the MD for this question and give to you early next week.

Best wishes