Q&A - PSLE Math

[nounou]

In a cinema, the ratio of the number of girls to the number of boys was 3:2. The ratio of the number of women to the number of boys was 5:4.

The ratio of the number of girls to the number of men was 2:5.
During the movie, 6 women and 27 men left the cinema.
The ratio of the number of women to the number of men then became 1:2.
a) Express the number of women as a fraction of the number of men at first. Leave your answer in its simplest form. --> 1/3
b) How many children were there in the cinema? --> 30 :?:
How to do (b)??? Please help. Many thanks. :thankyou:

[MathIzzzFun]

susutoo:

http://i49.tinypic.com/aoxq3b.jpg\">

Another Q, pls help

Hi

http://postimage.org/image/gyciubnmz/

cheers.

[MathIzzzFun]

dicoyote:

Packet A, Packet B and Packet C each contained some salt. At first, there were 200g more salt in Packet A than Packet B. Packet C had 3/4 of the amount of salt in Packet A. After 1/8 of the amount of salt in Packet A was transferred to Packet B, there was 82.15g of salt in Packet B. How many percent less salt were there in Packet C than Packet A at first?


Ans is 25%, thanks in advanced

Hi

Packet C : Packet A --> 3u : 4u
Difference --> 1u
Percentage less --> 1u/4u x 100% = 25%

cheers.

[MathIzzzFun]

susutoo:

Please help

1) There are more pens in box A than box B. 30% of the pens in box A is 60 more than 40% of the pens in box B. If 5% of the pens in box A is transfered to box B, there will be 300 more pens in box A than box B.
a) How many pens are there in box B?
b) How many percentage less pens are there in box B than box A?

Hi

40% of Box B --> 12 units ---- Box B --> 30 units
30% of A --> 12 units + 60 ----- Box A --> 40 units + 200
5% of Box A --> 2 units + 10
After transfer:

Box B --> 32 units + 10
Box A --> 38 units + 190
So, 38 units + 190 = 32 units + 10 + 300
1 unit --> 20

Box B --> 30 x 20 = 600 pens
Box A --> 40 x 20 + 200 = 1000 pens
(1000-600)/1000 x 100% = 40%
There are 40% less pens in Box B than in Box A.

cheers.

[mumworks]

:thankyou: very much Tianzhu for answering all my questions.

[kiasuaunt]

tianzhu:

kiasuaunt:

Hi.

Q1.
Mr Lee sold 15% of his cupcakes on Monday.
He sold 90 fewer cupcakes on Tuesday than on Monday.
He then sold 70 fewer cupcakes on Wednesday than on Tuesday.
On Thursday,he sold 330 cupcakes and found that he had half of his original number of cupcakes left.
How many cupcakes did he sell altogether?

Hi

A neat way is to use MD.

Hope this helps.

Best wishes

http://farm8.staticflickr.com/7220/7353643500_a0f577ed8d_z.jpg\">

:thankyou:

[pixiedust]

Here’s my solution :


girls:boys -> 3:2 -> 6:4
women:boys -> 5:4
girls:men -> 2:5 -> 6:15

girls:boys:women:men -> 6:4:5:15

At first : women:men -> 5:15 -> 1 :3
end : women: men -> 1:2

women : men
1u : 3u
-6 : -27
---------
1p: 2p

hence, 2u-12=3u-27; u=15
so we know, women at first = 1u = 15; men at first = 3u = 3*15=45
therefore (a) 15/45=1/3

since girls:boys:women:men -> 6:4:5:15
and women=15,men=45, therefore, (b) children=(6+4)*3=30

[isetan]

http://i47.tinypic.com/vzzksz.jpg\">


The figure is made up of a circle, identical semicircles and a square of side 12cm. P is the centre of the circle. What is the area of the shaded figure? Leave your answer correct to two decimal places.


Hi, can somebody helps this question? Thank u.

[susutoo]

MathIzzzFun:

susutoo:

http://i49.tinypic.com/aoxq3b.jpg\">

Another Q, pls help

Hi

http://postimage.org/image/gyciubnm
cheers.

Thank you
:salute:

[susutoo]

MathIzzzFun:

susutoo:

Please help

1) There are more pens in box A than box B. 30% of the pens in box A is 60 more than 40% of the pens in box B. If 5% of the pens in box A is transfered to box B, there will be 300 more pens in box A than box B.
a) How many pens are there in box B?
b) How many percentage less pens are there in box B than box A?

Hi

40% of Box B --> 12 units ---- Box B --> 30 units
30% of A --> 12 units + 60 ----- Box A --> 40 units + 200
5% of Box A --> 2 units + 10
After transfer:

Box B --> 32 units + 10
Box A --> 38 units + 190
So, 38 units + 190 = 32 units + 10 + 300
1 unit --> 20

Box B --> 30 x 20 = 600 pens
Box A --> 40 x 20 + 200 = 1000 pens
(1000-600)/1000 x 1
00% = 40%
There are 40% less pens in Box B than in Box A.

cheers.

Thank you!

Can you explain how to get 12 units for 40% of box B.