Q&A - P5 Math

[kyy]

Appreciate if someone can help with this question. Thanks!


The school bus can carry 24 adults or 40 children. If there are already 15 adults and 13 children on the bus, how many more children can the bus carry?

[tianzhu]

kyy:

Appreciate if someone can help with this question. Thanks!


The school bus can carry 24 adults or 40 children. If there are already 15 adults and 13 children on the bus, how many more children can the bus carry?

Hi

24 adults ------ 40 children
3 adults ------- 5 children

15 adults ------- 25 children

25+13 -------- 38

40 – 38 -------2

Best wishes

[keinic]

Hi


Appreciate if someone could help me with this question :

A tank 2/3 full of liquid A has a mass of 80 Kg. The same tank 1/4 full of liquid B has a mass of 44 Kg. The tank when full of liquid A is 36 Kg heavier than when it is full of liquid B. Find the mass of the empty tank.

[kyy]

tianzhu:

kyy:

Appreciate if someone can help with this question. Thanks!


The school bus can carry 24 adults or 40 children. If there are already 15 adults and 13 children on the bus, how many more children can the bus carry?

Hi

24 adults ------ 40 children
3 adults ------- 5 children

15 adults ------- 25 children

25+13 -------- 38

40 – 38 -------2

Best wishes

Hi Tianzu,

Thanks. I can understand. Often my problem is not knowing how to articulate the workings to my child without confusing her. Can you give me some tips please? How do I explain the concept of ratio being used here?

[MathIzzzFun]

keinic:

Hi


Appreciate if someone could help me with this question :

A tank 2/3 full of liquid A has a mass of 80 Kg. The same tank 1/4 full of liquid B has a mass of 44 Kg. The tank when full of liquid A is 36 Kg heavier than when it is full of liquid B. Find the mass of the empty tank.

Hi

mass of liquid B, when tank is full --> 12 units
mass of liquid A, when tank is full --> 12 units + 36

mass of liquid B, when tank is 1/4 full --> 3 units
mass of liquid A, when tank is 2/3 full --> 8 units + 24

Mass of Tank + 8 units + 24 --> 80
Mass of Tank + 3 units --> 44
5 units + 24 --> 36, 1 unit --> 2.4

Mass of Tank --> 44 - 3 x 2.4 = 36.8 kg

cheers.

[keinic]

Hi MathIzzzFun,


Thanks so much for the detailed explanation. It really helps!

MathIzzzFun:

keinic:

Hi

Appreciate if someone could help me with this question :

A tank 2/3 full of liquid A has a mass of 80 Kg. The same tank 1/4 full of liquid B has a mass of 44 Kg. The tank when full of liquid A is 36 Kg heavier than when it is full of liquid B. Find the mass of the empty tank.

Hi

mass of liquid B, when tank is full --> 12 units
mass of liquid A, when tank is full --> 12 units + 36

mass of liquid B, when tank is 1/4 full --> 3 units
mass of liquid A, when tank is 2/3 full --> 8 units + 24

Mass of Tank + 8 units + 24 --> 80
Mass of Tank + 3 units --> 44
5 units + 24 --> 36, 1 unit --> 2.4

Mass of Tank --> 44 - 3 x 2.4 = 36.8 kg

cheers.

[bookwormkids]

Q1.\tA sword tail costs 1 1/2 times as much as a guppy. David spent 3/8 of

his money on 60 sword tails and 70 guppies and still had $80 left.
(a) Find the cost of 10 guppies.
(b) Find the cost of 20 sword tails.

Q2. \tDavid has 2 1/2 times as much money as Kathy. After David spends
$44, Kathy has 1 1/2 times as much money as David. How much
money does Kathy have?

Thank you for your time.

[mathnoobs]

Hi Tianzhu

I was going through some old questions and came across this question.
http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=67&t=25121&start=60

After going through your answer, I'm still at a loss.
I believe my understanding of the question is at fault. Anyway, here is the question:

Aik Huat Provision sold 100 plates and bowls on a paticular day.
BY noon 5/8 of the plates and 12 bowls had been sold.
In the end, there was an equal number of plates and bowls.
How many bowls were there at first?

here is my understanding of it:
100 plates and bowls were sold at the end of the day.
In the morning 5/8 plates were sold and 12 bowls were sold.
In the beginning, before plates and bowls were sold, there were 8 units of plates.
In the afternoon, some more plates and bowls were sold.
In the end, an equal amount of plates and bowls were left unsold

Your solution says: 11 units + 12 = 100
how does one arrive at 11 units ? since 5 units of plates were sold in the morning, there are 3 units of plates left. However, since we don't know how many plates were sold in the afternoon, and how many plates are left.

I believe your 11 units is derived from 3 units of plates left and thus, there are also 3 units of bowls left. This is the part I do not understand, if there are 3 units of plates left, some amount must be sold in the afternoon, and some must remain left unsold. I'm totally confused on the comprehension of this question.

[small]

bookwormkids:

Q1.\tA sword tail costs 1 1/2 times as much as a guppy. David spent 3/8 of

his money on 60 sword tails and 70 guppies and still had $80 left.
(a) Find the cost of 10 guppies.
(b) Find the cost of 20 sword tails.

Thank you for your time.

Hi,

Solution for Q1

Q1. A sword tail costs 1 1/2 times as much as a guppy. David spent 3/8 of
his money on 60 sword tails and 70 guppies and still had $80 left.
(a) Find the cost of 10 guppies.
(b) Find the cost of 20 sword tails.


5/8 of David’s money ------ 80
1/8 of his money ------------ 16
3/8 of David money --------- 48

Price of each:
Sword tail : guppy
3u : 2u

Cost
Sword tail : guppy
60 x 3u : 70 x 2u
18u : 14u

32u = 48
1u – 3/2

a)\t
1 guppy ---------- 3/2 x 2 = 3
10 guppies ------- 3 x 10 = 30

b)\t
1 sword tail --------- 3/2 x 3 = 9/2
20 sword tails ------- 9/2 x 20 = 90

[small]

bookwormkids:

Q2. \tDavid has 2 1/2 times as much money as Kathy. After David spends
$44, Kathy has 1 1/2 times as much money as David. How much
money does Kathy have?

Thank you for your time.

Hi,
Solution for Q2

Before
David : Katty
5 : 2
15u : 6u

after David spent $44
David : Katty
2 : 3
4u : 6u

15u – 4u ------ 44
11u = 44
1u = 4

Katty ----- 6u
= 6 x 4
= 24

Kathy has $24