Q&A - P5 Math

[cimman]

Jamesbond:

http://i46.tinypic.com/161ant.jpg\">

Pl help....

the key thing to note in such problems is to figure out how to fit one shape onto another shape. That's easier said than done for some children who don't have the gift of spatial visualization. However, there are some general rules one can follow in the case of isosceles triangles and square.
http://i48.tinypic.com/1z4fnvb.png\">
Step 1: convert the triangles to a square. ie. a square is made up of 2 isosceles
triangles. The concept of tessellation is important here. Tessellate the triangle till you get a square.
http://i49.tinypic.com/dnha40.png\">

Step 2: draw lines to connect the vertices of the square together.
http://i46.tinypic.com/iqkgie.png\">

Step 3: from here, you should be able to pick out a unit shape (typically the smallest shape) that can be tessellated to fill the larger shape.
http://i47.tinypic.com/mvn347.jpg\">

The key point here is to tessellate the smaller regular shape to get the larger regular shape. You can view tessellation as a mirror reflection. Reflect the isosceles triangle till you get a square.
http://i47.tinypic.com/witu94.png\">

if you're ever stuck, start drawing lines to connect vertices of the regular shape, and then see if the smaller shapes that came out of that drawing can be tessellated to fill the larger shape.
I call this heuristic: Vertex Connection.

[elisammom]

Hi pls help


Alice is 7 yrs old n her mother is 33 yrs old. How many years later will her mother be 3 times as old as Alice?
Tia

[Jamesbond]

cimman:

Jamesbond:

http://i46.tinypic.com/161ant.jpg\">

Pl help....

the key thing to note in such problems is to figure out how to fit one shape onto another shape. That's easier said than done for some children who don't have the gift of spatial visualization. However, there are some general rules one can follow in the case of isosceles triangles and square.
http://i48.tinypic.com/1z4fnvb.png\">
Step 1: convert the triangles to a square. ie. a square is made up of 2 isosceles
triangles. The concept of tessellation is important here. Tessellate the triangle till you get a square.
http://i49.tinypic.com/dnha40.png\">

Step 2: draw lines to connect the vertices of the square together.
http://i46.tinypic.com/iqkgie.png\">

Step 3: from here, you should be able to pick out a unit shape (typically the smallest shape) that can be tessellated to fill the larger shape.
http://i47.tinypic.com/mvn347.jpg\">

The key point here is to tessellate the smaller regular shape to get the larger regular shape. You can view tessellation as a mirror reflection. Reflect the isosceles triangle till you get a square.
http://i47.tinypic.com/witu94.png\">

if you're ever stuck, start drawing lines to connect vertices of the regular shape, and then see if the smaller shapes that came out of that drawing can be tessellated to fill the larger shape.
I call this heuristic: Vertex Connection.

Thank you cimman.

[elisammom]

Hi another question pls help


There are 4 times as many red pens as blue pens. 415 red pens and 46 blue pens were removed. As a result, the number of blue pens is 3 times as many as red pens. How many blue pens were there at first?
Tia

[smartmummy]

elisammom:

Hi pls help


Alice is 7 yrs old n her mother is 33 yrs old. How many years later will her mother be 3 times as old as Alice?
Tia

m [][][]
a []
2u=33-7=26 {age difference}
3u=13*3=39
6 years later

[smartmummy]

elisammom:

Hi another question pls help


There are 4 times as many red pens as blue pens. 415 red pens and 46 blue pens were removed. As a result, the number of blue pens is 3 times as many as red pens. How many blue pens were there at first?
Tia

r [][][]46[][][]46[][][]46[][][]46
b[][][]46
[]- 1u
11u=415-(4*46)=231
1u=21
ans=3u+46=109

[smartmummy]

Jamesbond:

http://i50.tinypic.com/zv5r3l.jpg\">

Find the angle EDF.....pl help.

ans 20?
i assume it is a rectangle.
dfg=95
Dfe=85
efb=95
feb=45
assume dae=90
dea=60
deg=75
edf=20

[Jamesbond]

smartmummy:

Jamesbond:

http://i50.tinypic.com/zv5r3l.jpg\">

Find the angle EDF.....pl help.

ans 20?
i assume it is a rectangle.
dfg=95
Dfe=85
efb=95
feb=45
assume dae=90
dea=60
deg=75
edf=20

:thankyou:

[tianzhu]

redruby:

At a concert, the ratio of the number of women to the number of men is 3:1. The ratio of the number of women to the number of children is 1:4. What is the ratio of the adults to the number of children at the concert?

Hi

You may use MD or work using units.

Women: Men ----- 3:1

Women: Children ----- 1:4 -------3:12

The ratio for women is repeated in both set of ratios, so make it the same.

Adult: Children ----- 4:12 -------1:3

Best wishes

[tianzhu]

elisammom:

Hi another question pls help


There are 4 times as many red pens as blue pens. 415 red pens and 46 blue pens were removed. As a result, the number of blue pens is 3 times as many as red pens. How many blue pens were there at first?
Tia

Hi

You may use Units and Parts.

At first
Red: Blue ------ 4u:1u

Change
Red: Blue ------ -415:-46

In the end
Red: Blue ------ 1p:3p

4u – 415 ----- 1p
(x3)
12u – 1245 ----- 3p

1u – 46 ----- 3p

Make the parts the same

12u – 1245 ------ 1u – 46

11u ------- 1199

1u ------ 109

Number of blue pens at first ------ 1u ------ 109

Best wishes