Q&A - PSLE Math

[Mum1113]

Yu Xuan:

Mum1113:

Hi, may I get help to solve this and in case it been posted and answered before , from Nanyang 2010 papers :-


Tanks X and Y are each filled with some water. If water from Tank Y is poured into Tank X until the water in Tank X reaches the brim, there will be 8 litres of water left in Tank Y. If water from Tank X is poured into Tank Y until the water in Tank Y reaches the brim, there will be 26 litres of water left in Tank X. The ratio of the volume of Tank X to the volume of Tank Y is 5 : 3 . How many more litres of water are needed to fill both tanks to their brim ?

TIA

Ratio of X : Ratio of Y = 5 : 3
Difference in volume --> 5u -3u = 2u

There is some existing water in both tanks. The total volume of the existing water remains the same whether it is poured into Tank X or Y. Hence the 'excess' water is the difference in the volume of the two tanks. i.e.

2u --> 26 - 8 = 18
1u --> 9

Volume of Tank X --> 9 * 5 = 45
Volume of Tank Y --> 9 * 3 = 27

To find the existing volume of water in both tanks, we simply add the 8 litres of water to the volume of X ;

45 + 8 = 53

So the amount of watere required to fill up both tanks is
45 + 27 - 53 = 19 litres

thanks to iFruit and Yu Xuan, both algebra and models giving brilliant steps for understanding. dd usually uses models to solve problems, and algebra looks simpler for this mummy in diff era

[small]

Please help and many thanks in advance.


Question : There were 2668 chickend, ducks and goats in a farm. There were 20 fewer ducks than goats. When 58 goats, 1/4 of the chickens and 1/3 of ducks were killed in a flood, the number of ducks left was 4/9 of the number of chickens left. How many animals were killed altogether?

[tianzhu]

small:

Question : There were 2668 chickend, ducks and goats in a farm. There were 20 fewer ducks than goats. When 58 goats, 1/4 of the chickens and 1/3 of ducks were killed in a flood, the number of ducks left was 4/9 of the number of chickens left. How many animals were killed altogether?

Hi small

Please help to confirm numbers in red.

6U+20 +6U + 12U ------2668

Best wishes

[small]

Hi Tianzhu,


Thanks for your time, this question was given by the teacher and I will ask my DS to check with his teacher first. :oops:

If i did not guess wrongly, the question should be: There were 20 fewer goats than ducks.


6U - 20 + 6U + 12U = 2668 :idea:


anyway 祝您兔年行大运， 万事如意。。。

[tianzhu]

Hi small


Happy New Year.

You have another kid taking PSLE this year, I remember you have one kid who took his/her PSLE in 2009.

Best wishes

[small]

Hi Tianzhu,


Bravo, good memory... :celebrate:

You are right, my DD took her PSLE in 2009 and my DS is in P5 this year..

[small]

Please help on another question and once again many thanks.


Sigh, I only know to solve it in algebra method.

Question: A box of apples is shared among some people. If each person gets 5 apples, there will be 4 apples left. If each person gets 6 apples, there will be a shortage of 5 apples. How many people are there? My answer is 9 people

[Belle2011]

Dear all,

I have some questions to ask.

(1) A concert hall has 600 seats. 25% of the seats are premier seats while the rest are standard seats. How many premier seats must be added so that the number of premier seats will be increased to 70%?

(2) The lengths of 2 rectangles are 11m and 19m respectively. Their total area is 321m2. What is the difference in their areas?

(3) A group of people went hunting. On the average, 6 people hunted 5 rabbits, 15 people hunted 2 deer and 10 people hunted 1 buffalo. The total number of animals hunted was 6 more than the total number of people who went hunting. How many people went hunting?

I practically have no clue to start with especially with (3).

Thank-you.

Cheers,
Belle.

[small]

Hi Belle,


1) A concert hall has 600 seats. 25% of the seats are premier seats while the rest are standard seats. How many premier seats must be added so that the number of premier seats will be increased to 70%?

Solution:

My working was wrong, please referto Tianzhu's solution..

[small]

(3) A group of people went hunting. On the average, 6 people hunted 5 rabbits, 15 people hunted 2 deer and 10 people hunted 1 buffalo. The total number of animals hunted was 6 more than the total number of people who went hunting. How many people went hunting?


Solution:

My working wrong again :stupid: , please refer to Tianzhu's solution..