2010 PSLE Prelims

[blessedami]

Can anyone tell me if there is any inherent mistake in Red Swastika 2010 Prelim Paper Q 13, Paper 2 ? It is about three empty tanks kept side by side with a crack in the third and smallest tank at the bottom ? Though with the given data, the answer can be arrived at 10.2ml/min, then the students have to presume that the tank has been leaking for the 64 minutes that the tap was turned on.


Anyone who has tried the question, please advice as to how you interpreted the question. Thanks,

[fudgemum]

blessedami:

Can anyone tell me if there is any inherent mistake in Red Swastika 2010 Prelim Paper Q 13, Paper 2 ? It is about three empty tanks kept side by side with a crack in the third and smallest tank at the bottom ? Though with the given data, the answer can be arrived at 10.2ml/min, then the students have to presume that the tank has been leaking for the 64 minutes that the tap was turned on.


Anyone who has tried the question, please advice as to how you interpreted the question. Thanks,

Yes. The working should be wrong. The tank will start leaking once the water starts collecting in the third tank. I cannot solve this question. I did not post the question because I could not scan the diagram

[octopusmum]

HI


ds just tried out the paper this afternoon and we were stumped by 2 mcqs. The model answers did not seem to be correct. They are qtn 25 and 28. As both questions have diagrams, i didn’t type them out. would appreciate it if parents with kids in Red Swastika can share the answers for the above 2 qtns…

regards

[the kiasu student]

Hi all,

if any of you have some 2010 prelim questions, feel free to post it here. Thx! I hope this page can be very resourceful for all P6 pupils and parents and other P6 generations to come. :celebrate:

[PSLEmom]

Kindly do share the 2010 Prelims Science Q & A…TQ in advance.

[MdmKS]

Parents how did your child fare in the recent prelim? We seem to see a lot of good result in my ds school, especially maths. Was told to estimate T-score one can simply multiply the prelim average percentage by 3. It will be more or less there normally.

[the kiasu student]

Hi all,


My math teacher gave us a question from the nanyang prelims, still could not figure it out:

Mrs Reuten bought some pizzas for a group of children. The girls received thrice as many pizzas as the boys. There were an equal number of girls and boys. Each boy ate 2/9 of a pizza and the boys finished all the pizzas given to them. Each girl ate 1/6 of a pizza and the girls had 4½ pizzas left. How many pizzas did Mrs Reuten buy?

Pls help

[Pen88n]

the kiasu student:

Hi all,


My math teacher gave us a question from the nanyang prelims, still could not figure it out:

Mrs Reuten bought some pizzas for a group of children. The girls received thrice as many pizzas as the boys. There were an equal number of girls and boys. Each boy ate 2/9 of a pizza and the boys finished all the pizzas given to them. Each girl ate 1/6 of a pizza and the girls had 4½ pizzas left. How many pizzas did Mrs Reuten buy?

Pls help

Every boy eat 4/18 of a pizza whilst girl eat 3/18 of a pizza. Same # of boys and girls.

Model drawing:
Boys Pizza [][][][] 4 units
Girls Pizza [][][][][][][][][][][][] 3x4 units = 12 units

When boys ate up all their pizza (4 units), girls ate up only 3 units of their pizza. Left 9 units.

9 units = 4 & 1/2 pizza
1 unit = 1/2 pizza

Total Pizza bought: 16 units = 8 pizzas

[snowman.022851697]

Algebra method:


Let the amount of pizzas that the boys had be x.
Therefore, the girls would have 3x pizzas since they have 3 times as many pizzas as the boys.

Number of boys will be x/(2/9) as each boy ate 2/9 of a pizza.

X/(2/9) = x/1 x 9/2 = 9x/2 = 4.5x. Therefore, there are 4.5x boys.

Number of girls is similar
(3x-4.5*)/(1/6) = (3x - 4.5) x 6 = 6 x (3x - 4.5) = 6 x 3x - 6 x 4.5 = 18x - 27

Since the nos. of boys & girls Are similar, 4.5x = 18x - 27. This is a simple equation, rearrangement of unknowns are simple.

18X - 4.5x = 27
Then it all becomes straightforward.
13.5x = 27

Using a calculator, we deduce that x = 2.
Total amt of pizza = x + 3x = 4x = 2 x 4 = 8.

Answer: 8. So it's confirmed. This is basic algebra only, i've encountered problem sums in my p6 books where up to 3 unknowns were needed. When there's more than 1 unknown, you have to either substitute all other unknowns for one single unknown or use multiple equations to eliminate unknowns till you have only 1 left. Just a piece of advice(:

*reason why I used -4.5 is because the girls had 4.5 pizzas left.

Hope this helps(:

From a fellow p6.

[Pen88n]

the kiasu student:

Hi all,


My math teacher gave us a question from the nanyang prelims, still could not figure it out:

Mrs Reuten bought some pizzas for a group of children. The girls received thrice as many pizzas as the boys. There were an equal number of girls and boys. Each boy ate 2/9 of a pizza and the boys finished all the pizzas given to them. Each girl ate 1/6 of a pizza and the girls had 4½ pizzas left. How many pizzas did Mrs Reuten buy?

Pls help

My DS has another way of solving this problem. This is his method:

Ratio of Boy Pizza to Girl Pizza = 1:3

Assume Boy and Girl eat same proportion of pizza and finish all the pizzas they have been given, Girl will each eat 2/9 x 3 = 2/3 of pizza

But Girl eat only 1/6 each, so the difference: 2/3 - 1/6 = 1/2

Leftover is 4 and 1/2 pizza => (4 1/2) / (1/2) = 9 girls (or boys since they are same number)

So boys has 2/9 x 9 = 2 pizzas
and girls has (1/6 X 9) + 4 1/2 = 6 pizzas
and total is 8 pizzas