Q&A - PSLE Math

[Tang]

Dharma:

James Ang:

Question asked:

Mary and Peter attended a party. Peter met with 4 times as many boy as girls while Mary met with 5 times as many boys as girls. How many boys and girls were at the party?

http://www.postimage.org/

If we substitute p = 5 into the model for Mary,
Boys + Peter = 5 x 5 + 1 = 26 boys [should be 25]

Girls + Mary = 5 - 1 + 1 = 5 girls [should be 6]


There is an error in labelling in the model for Mary. Should be

Mary met --> Boys (p - 1) ; Girls (p) ; Peter (1)

you will then get 25 boys and 6 girls.

[Dharma]

Thanks Tang.

http://www.postimage.org/

[N3SKiasu]

Hi, kindly help with this question:


In a classroom, when a boy stands up, the number of boys sitting becomes 4/5 of the number of girls sitting. On the other hand, when a girl stands up, the number of girls sitting becomes 8/7 of the number of boys sitting. How many boys and girls are there in the class altogether?

Question looks similar to the Mary & Peter question but still can't figure out. :oops: pls help.

[Dharma]

N3SKiasu:

Hi, kindly help with this question:


In a classroom, when a boy stands up, the number of boys sitting becomes 4/5 of the number of girls sitting. On the other hand, when a girl stands up, the number of girls sitting becomes 8/7 of the number of boys sitting. How many boys and girls are there in the class altogether?

Question looks similar to the Mary & Peter question but still can't figure out. :oops: pls help.

http://www.postimage.org/

[Drdj]

Dear all,


Could you explain the solution of this sum from Ai Tong 2008?
The triangles are both isoceles (45, 45, 90), but I just can't seem to get it
Thanks in advance

http://www.postimage.org/image.php?v=Pq9MGnr

[JustKP]

Drdj:

Dear all,


Could you explain the solution of this sum from Ai Tong 2008?
The triangles are both isoceles (45, 45, 90), but I just can't seem to get it
Thanks in advance

http://www.postimage.org/image.php?v=Pq9MGnr

Hi, just joined the 2 triangles together to get an isoseles triangle of both sides 10cm (radius of the circle).

[kiasiparent]

Drdj:

Dear all,


Could you explain the solution of this sum from Ai Tong 2008?
The triangles are both isoceles (45, 45, 90), but I just can't seem to get it
Thanks in advance

http://www.postimage.org/image.php?v=Pq9MGnr

There are two smaller and unshaded triangles inside the semi circle. These two triangles can be rearranged to form a square of diagonal 10 cm.
Area of square = diagonal x diagonal / 2 = 10 x 10 / 2 = 50

Then take area of semi circle - 50

[Drdj]

Dear JustKP,


Thanks so much !!

JustKP:

Drdj:

Dear all,

Could you explain the solution of this sum from Ai Tong 2008?
The triangles are both isoceles (45, 45, 90), but I just can't seem to get it
Thanks in advance

http://www.postimage.org/image.php?v=Pq9MGnr

Hi, just joined the 2 triangles together to get an isoseles triangle of both sides 10cm (radius of the circle).

[Drdj]

Dear all,


Could you help me to solve this?
Thanks a lot
http://www.postimage.org/image.php?v=aV15TSLS

[JustKP]

Drdj:

Dear all,


Could you help me to solve this?
Thanks a lot
http://www.postimage.org/image.php?v=aV15TSLS

Angle AED is 90, so angle DAE is 27. Thus angle x is 36 (90-27-27).