Q&A - PSLE Math

[tianzhu]

underthesea:

Can someone help me to solve this question without using algebra.


Tank A and tank B contain some water.
If 46.5ml of water is drained out from tank A, the volume of the water in tank A will be 60% that of the water in tank B.
If 35.2ml of water is drained out from tank B, the volume of water in tank B will be 85% that of the water in tank A.
What is the total volume of water in tank A and tank B?

TIA.

Hi

Thsi question has been discussed before.

Hope this helps.

Best wishes

http://farm7.staticflickr.com/6166/6162256981_fb0d5c4e9e_z.jpg\">

[Tiramisu Coco]

MathIzzzFun:

Tiramisu Coco:

[quote=\"tianzhu\"]Hi, need help for this qtn.

Thank u.

http://www.flickr.com/photos/82618212@N07/7568230484

Hi

Good Morning.

Where is this question from?

It should be a breeze for secondary school students who have knowledge about tangential properties.

For primary schools, it might pose some challenges.

I think one way is show is to use a pair of compasses, draw two arcs from the centre of the circle to touch the longest side of the triangle (30 cm), say at a point X.

(24 – r ) + (18 – r) ------- 30

r + r ------- 42 – 30

r ------- 12/2 ------- 6

Try it out.

Hope this helps.

Best wishes

Hi Tianzhu,
Thks for your solution.
Pls enlighten why is
(24-r)+(18-r) --- 30?

Thks!

Hi

This is not a standard P6/PSLE question - more likely a competition question, because this requires student to know properties of tangent, congruent triangles.

http://i46.tinypic.com/219bfx2.png\">

BY=BZ (by congruent triangles: OY=OZ, OB=OB, angle OZB=angle OYB=90 deg)
CX=CZ (by congruent triangles)
BY+CX = BZ + CZ
24-R + 18-R = 30, R --> radius of circle

cheers.[/quote]Hi tianzhu & MathIzzzfun,
Thks for your help.
A friend shared this qtn that she got from a pri maths tuition ctr's FB pg, which stated that to solve the qtn, students need to draw lines, use ratio & unit transfer method(2 variables concepts). Wonder if it's relevant for p6 to know how to solve this type of qtns.

[tianzhu]

Tiramisu Coco:

Hi tianzhu & MathIzzzfun,
Thks for your help.
A friend shared this qtn that she got from a pri maths tuition ctr's FB pg, which stated that to solve the qtn, students need to draw lines, use ratio & unit transfer method(2 variables concepts). Wonder if it's relevant for p6 to know how to solve this type of qtns.

Hi

There are alternate ways to reach a solution.

I’ve yet to see such a question during the time when my kid was doing his PSLE.

Please check with your school teachers to see whether this question is relevant or not in P6 syllabus.

Yes, you’ll need to draw lines from the centre of the circle to the points where the circle touches the triangle at right angles.

Draw an arc from where the circle touches the 18cm line. Draw another arc from where the circle touches the 24 cm line. These two arcs will intersect the 30 cm line at the same point X.

From here, it can be seen as (24-r) + (18-r) ------30.

Best wishes

[MathIzzzFun]

Tiramisu Coco:

Hi tianzhu & MathIzzzfun,
Thks for your help.
A friend shared this qtn that she got from a pri maths tuition ctr's FB pg, which stated that to solve the qtn, students need to draw lines, use ratio & unit transfer method(2 variables concepts). Wonder if it's relevant for p6 to know how to solve this type of qtns.

Hi

here's a solution using P6 method .. areas of square and triangle

http://i45.tinypic.com/4jur89.png\">

cheers.

[tianzhu]

Hi


Another way to look at your question.

Please refer to MathIzzzFun ‘s diagram.

From the centre of the circle o, draw three lines to touch A,B and C of the triangle.

This will give you 3 smaller triangles of height equal to radius r.

Area of triangle ABC ------ ½1824 ------- 216

Area of triangle AOC ------ ½18r ------ 9r

Area of triangle AOB ------ ½24r ------ 12r

Area of triangle BOC ------ ½30r ------ 15r

9r+12r+15r ------- 36r

36r ------ 216

r ------- 6

Best wishes

[Shimmer]

Can someone help on this question ?


1) During a camp, Mrs chan ordered an equal number of buns and cakes for breakfast from a bakery. The ratio of the cost of a bun to the cost of a cake was 3:1. 60% of the buns and 40% of the cakes were eaten and that cost her $264.
A) if each bun cost $1.20, how many buns did she order ?
b) if the bakery agreed only to change for the buns and cakes consumed, how many would she save if only 70% of the buns and 60% of the cakes were eaten at the end of he camp.

[Shimmer]

Need help !


Thanks in advance !

The average height of 6 pupils was 170cm. The average height of the first 4 pupils was 15cm more than the average height of the remaining 2 pupils, Agnes and Tony.
A) find the average height of the remaining 2 pupils, Agnes and Tony.
B) Agnes was 25cm taller than Tony. Find Agnes’s actual height.

[Shimmer]

Need help on this question. Thks


Eugene,Freddy and George had some playing cards .Freddy had 200 more playing cards than Eugene.George had 3/4 the number of cards Freddy had. After George lost 1/6 of his cards to Eugene , he had 320 fewer cards tha Eugene. What was the ratio of cards Eugene had to the number of cards Freddy had to the number of cards to the number of cards George had in the end?

[MathIzzzFun]

Shimmer:

Can someone help on this question ?


1) During a camp, Mrs chan ordered an equal number of buns and cakes for breakfast from a bakery. The ratio of the cost of a bun to the cost of a cake was 3:1. 60% of the buns and 40% of the cakes were eaten and that cost her $264.
A) if each bun cost $1.20, how many buns did she order ?
b) if the bakery agreed only to change for the buns and cakes consumed, how many would she save if only 70% of the buns and 60% of the cakes were eaten at the end of he camp.

Hi
each bun --> $1.20, buns sold --> 60u
each cake --> $0.40, cakes sold --> 40u
Total cost of buns sold --> 72u
Total cost of cakes sold --> 16u
88u --> $264
1u --> 3
a) Number of buns ordered = 100 x 3 = 300

b) cost of 70% buns + 60% cakes --> 210 buns + 180 cakes --> 210 x 1.2 + 180 x 0.4 = $324
300 buns + 300 cakes --> 300 x 1.60 = $480
savings --> $480 - $324 = $156

cheers.

[MathIzzzFun]

Shimmer:

Need help on this question. Thks


Eugene,Freddy and George had some playing cards .Freddy had 200 more playing cards than Eugene.George had 3/4 the number of cards Freddy had. After George lost 1/6 of his cards to Eugene , he had 320 fewer cards tha Eugene. What was the ratio of cards Eugene had to the number of cards Freddy had to the number of cards to the number of cards George had in the end?

Hi
Eugene --> 8 units
Freddy --> 8 units + 200
George --> 6 units + 150

George lost 1/6 to Eugene, 1/6 --> 1 unit + 25

In the end:
Freddy --> 8 units + 200
George --> 5 units + 125
Eugene --> 9 units + 25

9 units + 25 = 5 units + 125 + 320
1 unit --> 105

...i think you can complete the solution..

cheers.