Q&A - PSLE Math

[pixiedust]

Appreciate any help with the following :


There are 14 pupils in a class.
If each pupil exchanges one sticker with every other one, how many sticker exchanges are made ?

[tianzhu]

pixiedust:

Appreciate any help with the following :


There are 14 pupils in a class.
If each pupil exchanges one sticker with every other one, how many sticker exchanges are made ?

Hi

Draw a diagram to see a pattern.

(13+12+11+10+9+8+7+6+5+4+3+2+1)-------- 91 sticker exchanges

Best wishes

[avell]

Dear all


Pls help me for the following questions:-

Qn (1)
4/5 of John’s money is equal to 3/8 of Sarah’s money. Express Sarah’s money as a ratio of John’s money in it simplest form (draw a model to help you to solve the sum.

Qn (2)
The ratio of boys and girls on a school bus was 2 : 3. When 16 girls alighted from the bus, the ratio of the remaining boys to girls became 6:5. Find the number of children who remained on the bus.

[jieheng]

avell:

Dear all


Pls help me for the following questions:-

Qn (1)
4/5 of John's money is equal to 3/8 of Sarah's money. Express Sarah's money as a ratio of John's money in it simplest form (draw a model to help you to solve the sum.

Hi ,

Q1)

J [ ][ ][ ][ ][ ] 5 units

S [ -][ -][ -][ -][ -][ -][ -][ -] 8 units

To solve the question , need to modify the model , so that the units in Red and Blue are equal

J * 3 and S * 4

J 15 units

S 32 units

Ratio of Sarah's money to John's money = 32 : 15 (Ans)

****************************************************
Faster way to solve this type of question without using the model is to change the numerators of two variables to the same number .

John Sarah
4/5 3/8

Change to

John Sarah
12/15 12/32

Ratio of Sarah's money to John's money = 32 : 15 (Ans)

[jieheng]

avell:

Dear all


Pls help me for the following questions:-

Qn (2)
The ratio of boys and girls on a school bus was 2 : 3. When 16 girls alighted from the bus, the ratio of the remaining boys to girls became 6:5. Find the number of children who remained on the bus.

Old Ratio
B [ ][ ] 2u

G [ ][ ][ ] 3u

New Ratio
B [ ][ ][ ][ ][ ][ ] 6u

G [ ][ ][ ][ ][ ] 5u

Since the number of the boys remained the same throughout the journey ,
modify the old ratio of the boys from 2 units to 6 units

Modified old ratio
B [ ][ ][ ][ ][ ][ ] 6u

G [ ][ ][ ][ ][ ][ ][ ][ ][ ] 9u

Compare the units of the girls of modified old ratio and new ratio ,

4 units = 16
1 unit = 4

Number of children remained on the bus = 11 units (6 units of boys and 5 units of girls) = 11 * 4 = 44 (Ans)

[avell]

jieheng:

avell:

Dear all


Pls help me for the following questions:-

Qn (2)
The ratio of boys and girls on a school bus was 2 : 3. When 16 girls alighted from the bus, the ratio of the remaining boys to girls became 6:5. Find the number of children who remained on the bus.

Old Ratio
B [ ][ ] 2u

G [ ][ ][ ] 3u

New Ratio
B [ ][ ][ ][ ][ ][ ] 6u

G [ ][ ][ ][ ][ ] 5u

Since the number of the boys remained the same throughout the journey ,
modify the old ratio of the boys from 2 units to 6 units

Modified old ratio
B [ ][ ][ ][ ][ ][ ] 6u

G [ ][ ][ ][ ][ ][ ][ ][ ][ ] 9u

Compare the units of the girls of modified old ratio and new ratio ,

4 units = 16
1 unit = 4

Number of children remained on the bus = 11 units (6 units of boys and 5 units of girls) = 11 * 4 = 44 (Ans)

Hi Jieheng
Many thanks. I really appreciate it.

[jieheng]

avell:

Hi Jieheng
Many thanks. I really appreciate it.

Hi avell ,

You are welcome.

[peggy]

avell:

Dear all


Pls help me for the following questions:-

Qn (1)
4/5 of John's money is equal to 3/8 of Sarah's money. Express Sarah's money as a ratio of John's money in it simplest form (draw a model to help you to solve the sum.

Qn (2)
The ratio of boys and girls on a school bus was 2 : 3. When 16 girls alighted from the bus, the ratio of the remaining boys to girls became 6:5. Find the number of children who remained on the bus.

Hi,

Any MD please? I'm quite lost!

[MathIzzzFun]

peggy:

avell:

Dear all


Pls help me for the following questions:-

Qn (1)
4/5 of John's money is equal to 3/8 of Sarah's money. Express Sarah's money as a ratio of John's money in it simplest form (draw a model to help you to solve the sum.

Qn (2)
The ratio of boys and girls on a school bus was 2 : 3. When 16 girls alighted from the bus, the ratio of the remaining boys to girls became 6:5. Find the number of children who remained on the bus.

Hi,

Any MD please? I'm quite lost!

Hi

Here's the MD for Q1 & Q2.



http://postimage.org/image/290mem8sk/


http://postimage.org/image/g4imrx0k/

cheers.

[peggy]

MathIzzzFun,


Many thanks !


Regards,
peggy