Q&A - PSLE Math

[tianzhu]

Chalupa:

Hi please help to solve this problem.

There were 1600 pupils in a primary school. When the number of boys increased by 76 and the number of girls decreased by 4% , the total enrollment in the school increased by 3%. How many boys were in the school at first..
Thanks in advance.

Hi

It helps to start with a simple diagram.

1.03*1600 ----- 1648

76 – 48 ------ 28

4% of girls ------- 28

1% of girls ------- 7

100% of girls ------- 700

Number of boys@first ------- 900

Best wishes

[PiscesLeo]

Posted this in P5 thread but there’s no reply so hope to get help here.


Tank A and tank B are identical. 5/6 of tank A and 1/4 of tank B are filled with water. The mass of tank B with its contents is 7/13 of the mass of tank A with it’s contents. The total mass of the two tanks with their contents is 1400g. Find the mass of the empty tank.

Thank you very much

[MathIzzzFun]

PiscesLeo:

Posted this in P5 thread but there's no reply so hope to get help here.


Tank A and tank B are identical. 5/6 of tank A and 1/4 of tank B are filled with water. The mass of tank B with its contents is 7/13 of the mass of tank A with it's contents. The total mass of the two tanks with their contents is 1400g. Find the mass of the empty tank.

Thank you very much

mass of empty tank + 5/6 contents (tank A) --> 13/20 x 1400g = 910g
mass of empty tank + 1/4 contents (tank B) --> 1400g - 910g = 490g

(5/6-1/4) contents --> 910g - 490g
7/12 contents --> 420g
1/12 contents --> 60g

mass of empty tank --> 910g - 10 x 60g = 310g

cheers.

[Chalupa]

Please help me in this question


There were 1600 pupils in a primary school.When the number of boys increased by 76 and the number of girls decreased by 4%,the total enrollment in the school increased by 4%.How many boys were there in the school at first?

[Maths Hub]

PiscesLeo:

Posted this in P5 thread but there's no reply so hope to get help here.


Tank A and tank B are identical. 5/6 of tank A and 1/4 of tank B are filled with water. The mass of tank B with its contents is 7/13 of the mass of tank A with it's contents. The total mass of the two tanks with their contents is 1400g. Find the mass of the empty tank.

Thank you very much

(i)Difference (Fraction):
5/6 - 1/4 = 7/12

(ii)Difference (Weight):
20 units --> 1400
1 unit--> 1400/20 = 70
13-7 = 6
6 X 70 = 420

(iii) Putting both (i) and (ii) together, we will get:
7/12--> 420 g
1/12--> 420/7 = 60 g
1/4--> 180 g

(iv) We can also get the weight of the tank with 1/4 water from (ii):
Tank+1/4 water--> 70 X 7 = 490

(v) Now we find the answer using (iii) and (iv):
Empty tank--> 490 - 180 = 310 g

Hope that helps.

[CDE]

Anyone can help with this question?


A and B has some sweet. If A eat 2 a day, and B eat 1 a day - A will have 68 left while B has none. If A eat 1 a day and B eat 2 a day - A will have 122 left while B has none.
How many sweet do they have at first?

Thanks

[Maths Hub]

Chalupa:

Please help me in this question


There were 1600 pupils in a primary school.When the number of boys increased by 76 and the number of girls decreased by 4%,the total enrollment in the school increased by 4%.How many boys were there in the school at first?

104% X 1600 = 1664
1600 + 76 = 1676
So there was a drop of 1676-1664 = 12
4% of girls--> 12
100% of girls --> 12 X 25 = 300
Boys at first --> 1600 - 300 = 1300

Hope that helps.

[PiscesLeo]

:thankyou: MathIzzzFun and Maths Hub :thankyou:

[iCreative Math]

A and B has some sweet. If A eat 2 a day, and B eat 1 a day - A will have 68 left while B has none. If A eat 1 a day and B eat 2 a day - A will have 122 left while B has none. How many sweet do they have at first?


The answer is A has 140 sweets and B has 36 sweets at first.

I have coincidentally recorded two YouTube videos recently explaining a similar question. The questions have different figures but the concept tested and hence the problem-solving method is identical.

You might want to get your child to view the YouTube videos.

I have recorded two different videos, one using the \"normal\" method and another using the \"Guess & Check\" method.

The generic simplified problem-solving methods taught in the videos will apply to all similar questions of this nature.

Hope it is helpful.


Best Regards
iCreative Math

YouTube Lesson Videos:
http://www.youtube.com/watch?v=JXpXuz2Tqf4 (PSLE “Double-IF” Question)

http://www.youtube.com/watch?v=jcU2hv-GTBE (PSLE “Double-IF” Question using “Guess & Check” Method)

[Mary Joy]

Please help me with this question!Thank you


In an auditorium,30% of the seats are reserved for the platinum class.The ratio of the number of seats for silver class to the number of seats for gold class is 12:13. After the auditorium underwent a renovation,the number of seats in the auditorium is increased by 20%. There are now 1440 seats reserved for the platinum class.

a) how many seats are reserved for the silver and gold class after the renovation?

b) how many seats are reserved for the silver class before the renovation?