Q&A - PSLE Math

[Angel25]

A rectangular tank, 1m long, 80cm wide and 40cm high was filled with some water. 8 metal cubes of equal volume were placed in the water and 1200cm3 of water overflowed from the tank. Jacob then took 3 metal cubes from the water carefully and the height of the water in the tank was 37cm, (taking 1litre=1000cm3)

a) what was the volume of each metal cube?
b) what was the length of each metal cube?
c) how many litres of water were in the tank before 8 metal cubes were put in?

[Angel25]

This is a P6 Question:-


Two tins of different sizes weigh individually. The bigger tin measuring 1m by 50cm by 40cm has a mass of 24kg when it is filled with 100 metal bars, each weighing 200g.
Find the mass of the smaller rectangular empty tin which is made of the same material and is 80cm by 30cm by 20cm.
(heuristics skills - Before - After concept)

[ET-PH]

Hi,


This is a P5 question from Ai Tong SA1. Can someone help ? Thanks.

Sandra had twice as many apples as oranges at first. She removed 4 apples and 3 oranges each time. In the end, there were 18 apples and 1 orange left. How many fruits did Sandra have at first ?

[MathIzzzFun]

ET-PH:

Hi,


This is a P5 question from Ai Tong SA1. Can someone help ? Thanks.

Sandra had twice as many apples as oranges at first. She removed 4 apples and 3 oranges each time. In the end, there were 18 apples and 1 orange left. How many fruits did Sandra have at first ?

Hi

this was discussed in earlier thread - http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=27&t=280&p=441619&hilit=Sandra+had+twice+as#p441619

http://www.flickr.com/photos/62167097@N02/5691800011/in/photostream

cheers.

[ET-PH]

MathIzzzFun:

ET-PH:

Hi,


This is a P5 question from Ai Tong SA1. Can someone help ? Thanks.

Sandra had twice as many apples as oranges at first. She removed 4 apples and 3 oranges each time. In the end, there were 18 apples and 1 orange left. How many fruits did Sandra have at first ?

Hi

this was discussed in earlier thread - http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=27&t=280&p=441619&hilit=Sandra+had+twice+as#p441619

http://www.flickr.com/photos/62167097@N02/5691800011/in/photostream

cheers.

Thanks MathIzzzFun... Cheers

[Angel25]

Hi there,

Can anyone help me with these two questions??

Q1) A rectangular tank, 1m long, 80cm wide and 40cm high was filled with some water. 8 metal cubes of equal volume were placed in the water and 1200cm3 of water overflowed from the tank. Jacob then took 3 metal cubes from the water carefully and the height of the water in the tank was 37cm, (taking 1litre=1000cm3)
a) what was the volume of each metal cube?
b) what was the length of each metal cube?
c) how many litres of water were in the tank before 8 metal cubes were put in?


Q2)
Two tins of different sizes weigh individually. The bigger tin measuring 1m by 50cm by 40cm has a mass of 24kg when it is filled with 100 metal bars, each weighing 200g.
Find the mass of the smaller rectangular empty tin which is made of the same material and is 80cm by 30cm by 20cm.

[MathIzzzFun]

Angel25:

Hi there,

Can anyone help me with these two questions??

Q1) A rectangular tank, 1m long, 80cm wide and 40cm high was filled with some water. 8 metal cubes of equal volume were placed in the water and 1200cm3 of water overflowed from the tank. Jacob then took 3 metal cubes from the water carefully and the height of the water in the tank was 37cm, (taking 1litre=1000cm3)
a) what was the volume of each metal cube?
b) what was the length of each metal cube?
c) how many litres of water were in the tank before 8 metal cubes were put in?


Q2)
Two tins of different sizes weigh individually. The bigger tin measuring 1m by 50cm by 40cm has a mass of 24kg when it is filled with 100 metal bars, each weighing 200g.
Find the mass of the smaller rectangular empty tin which is made of the same material and is 80cm by 30cm by 20cm.

Hi

http://i51.tinypic.com/4q4j95.jpg\">

http://i56.tinypic.com/4vpf0k.jpg\">

cheers.

[is_me_lblue]

Hi, pls confirm my answer.


Figure. Number of oval
1. 1
2. 5
3. 13
4. 25
5. 41

Below answer for the Q is given in the answer sheet.
Q:how many ovals will there be in Figure 87 ?
A:14695 ( my answer is 705)


Q: which figure will have 5305 ovals ?
A: 5305(this is for sure wrong)

[MathIzzzFun]

is_me_lblue:

Hi, pls confirm my answer.


Figure. Number of oval
1. 1
2. 5
3. 13
4. 25
5. 41

Below answer for the Q is given in the answer sheet.
Q:how many ovals will there be in Figure 87 ?
A:14695 ( my answer is 705)


Q: which figure will have 5305 ovals ?
A: 5305(this is for sure wrong)

Hi is_me_lblue,

a) Number of ovals in fig 87
= 1 + (1+2+3+4+5+...+85+86) x 4
= 14965

b) Figure with 5305 ovals = Figure 52

Number of ovals in Figure n =
1+ (1+2+3+4+5+...+n-1) x 4 = 5305
(1+2+3+4+5+...+n-1) = 1326
n=52

cheers.

[Dharma]

Fig 1 => 1

Fig 2 => 5 = 4 + 1
Fig 3 => 13 = 9 + 4
Fig 4 => 25 = 16 + 9
Fig 5 => 41 = 25 + 16
Fig n => n^2 + (n - 1)^2

Fig 87 => 87^2 + 86^2 = 14965 ovals

If number of ovals is 5305

Take the average of n^2 and (n-1)^2 = 5305/2 = 2652.5
Square root of 2652.5 = 51.5

n is the next whole number > 51.5 (n = 52)

52^2 + 51^2 = 5305 (Fig. 52 has 5305 ovals)