Q&A - PSLE Math

[tianzhu]

Michaelia0816:

I need to do this correction, help me by giving me the statement and answer, I will try to understand it!


The ratio of the volume of water on a pail to the volume of water in a basin 3:2. After 3/4 of the water in the basin is poured out,the basin contains 200 ml less than the pail. How much water does the pail contains?

Hi

Pail:Basin ------ 3:2 ------ 6:4

Pail ------ 6 units

Basin ------ 1 unit (After 3/4 of the water in the basin is poured out)

5 units ------- 200

1 unit ------ 40

Pail ------- 6*40 -------240

Best wishes

[tianzhu]

Michaelia0816:

This questions needs help, ok!

1) A baker packs some cookies into 8 large bags and 12 small bags. Each large bag has 5 more cookies than each small bag. 1/3 of the cookies are packed in the large bags while 4/9 of the cookies are packed in the small bags. the remaining cookies are put in a tin.
A) What faction of the cookies is put in the tin?
B) How many cookies are put into bags?

Need the whole method as it is a 5 marks question!!!! Step by step answer!!! And if the answer for A is 2/9? If not, pls correct me and give me the answer! I don know how to do B!

Hi

Your answer of 2/9 is correct.

For part (b), a neat way is to use MD. If you’re comfortable with units, you may also use it.

From part (a), we gather the following information.

8 large bags ----- 3 units

12 small bags ------- 4 units

3 small bags -------- 1 unit

Therefore , 8 large bags --------- 9 small bags

8 small bags + 40 ------- 9 small bags

1 small bag ------- 40

Number of cookies @bags ------- 840

Best wishes

[tianzhu]

brastilava:

Hi Tianzhu, thanks so much for the clear pictorial.

Hi

You're welcome.

Best wishes

[tianzhu]

Michaelia0816:

Thank you Tianzhu for the rose question!

Hi

You're welcome.

Best wishes

[alderbaran]

Michaelia0816:

I need to do this correction, help me by giving me the statement and answer, I will try to understand it!


The ratio of the volume of water on a pail to the volume of water in a basin 3:2. After 3/4 of the water in the basin is poured out,the basin contains 200 ml less than the pail. How much water does the pail contains?

Concept: Because we are pouring away 3/4 of the water from the basin, we should make the basin ratio a multiple of 4.

P : B
3 : 2 (before pouring water)
6 : 4 (multiply the ratio by 2)
6 : 1 (after pouring 3/4 of water from basin)

Pail - Basin:
5 units = 200ml
1 unit = 40ml

Pail:
6 units = 6*40ml = 240ml

[Michaelia0816]

Tianzhu, help!


The figure below is formed by stacking 4 cardboard of equilateral triangles one on top of another. The triangles have sides 3cm,4cm,5cm and 6cm. The 6cm piece is triangle ABC. It is placed at he bottom of the stack followed by the 5cm piece, then the 4cm piece and the 3cm piece is right on top. What faction of the triangle ABC has only 2 layers of cardboard?

I am not sure of the phrase highlighted in red! Do give step by step answer!

[Michaelia0816]

tianzhu:

Michaelia0816:

I need to do this correction, help me by giving me the statement and answer, I will try to understand it!


The ratio of the volume of water on a pail to the volume of water in a basin 3:2. After 3/4 of the water in the basin is poured out,the basin contains 200 ml less than the pail. How much water does the pail contains?

Hi

Pail:Basin ------ 3:2 ------ 6:4

Pail ------ 6 units

Basin ------ 1 unit (After 3/4 of the water in the basin is poured out)

5 units ------- 200

1 unit ------ 40

Pail ------- 6*40 -------240

Best wishes

Thank for this too!

[Michaelia0816]

tianzhu:

Michaelia0816:

This questions needs help, ok!

1) A baker packs some cookies into 8 large bags and 12 small bags. Each large bag has 5 more cookies than each small bag. 1/3 of the cookies are packed in the large bags while 4/9 of the cookies are packed in the small bags. the remaining cookies are put in a tin.
A) What faction of the cookies is put in the tin?
B) How many cookies are put into bags?

Need the whole method as it is a 5 marks question!!!! Step by step answer!!! And if the answer for A is 2/9? If not, pls correct me and give me the answer! I don know how to do B!

Hi

Your answer of 2/9 is correct.

For part (b), a neat way is to use MD. If you’re comfortable with units, you may also use it.

From part (a), we gather the following information.

8 large bags ----- 3 units

12 small bags ------- 4 units

3 small bags -------- 1 unit

Therefore , 8 large bags --------- 9 small bags

8 small bags + 40 ------- 9 small bags

1 small bag ------- 40

Number of cookies @bags ------- 840

Best wishes

Thanks too!

[tianzhu]

Michaelia0816:

Step by step answer pls, cause don know lah!


2) The two tanks A and B was filled with some water. A is 1/5 filled with water while B is 1/3 with water. Water flows into both tanks at the same time from taps each at he rate of 1.8 litres per minutes. How long will it take for the water in both tanks to be of the same height?( Give your answer in minutes and seconds)
Tank A---- Height: 40cm
Length: 60cm
Breath: 10cm

Tank B---- Height: 36 cm
Length: 50 cm
Breath: 20 cm

Hi

At first

Water height@A ------- 8cm
Water height@B ------- 12cm

1.8 litres per minutes -------- 1800 cubic cm/min

In 1 min, height of water@A raised by 1800/600 or 3cm

In 1 min, height of water@B raised by 1800/1000 or 1.8cm

Difference in height ------- 1.2 cm

12-8 ------4

Time taken for water to be at same level ------- 4/1.2 ------ 3 mins 20 secs

Best wishes

[tianzhu]

Michaelia0816:

Tianzhu, help!


The figure below is formed by stacking 4 cardboard of equilateral triangles one on top of another. The triangles have sides 3cm,4cm,5cm and 6cm. The 6cm piece is triangle ABC. It is placed at he bottom of the stack followed by the 5cm piece, then the 4cm piece and the 3cm piece is right on top. What faction of the triangle ABC has only 2 layers of cardboard?

I am not sure of the phrase highlighted in red! Do give step by step answer!

Hi

Please post the figure.

Best wishes