Q&A - PSLE Math

[MathIzzzFun]

Mary Joy:

please help me with these questions thank you


1.at first John had some money.he spent 1/4 of it on a t-shirt and 2/5 of the remainder on a pair of shoes.After that,his parents gave him $120.The ratio of the total amount of money he had at the end to the amount of money he had at first was 5:4.How much money did John have at first?

How many sweets did ken buy?

At first, John's money --> 20 units
Amount left after buying shoes --> 3/5 x 3/4 x 20 units = 9 units

In the end, John's money --> 9 units + $120

John's money, in the end : at first = 5 : 4 --> 25 units : 20 units

so, 9 units + $120 = 25 units
1 unit --> $ 7.50

John's money, at first --> 20 x $ 7.50 = $ 150

cheers.

[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.

[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: