Q&A - PSLE Math

[Tiramisu Coco]

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 ------ ½*18*24 ------- 216

Area of triangle AOC ------ ½*18*r ------ 9r

Area of triangle AOB ------ ½*24*r ------ 12r

Area of triangle BOC ------ ½*30*r ------ 15r

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

36r ------ 216

r ------- 6

Best wishes

Hi,
Thks MathIzzzFun for explaining the equation (24-r)+(18-r)=30 with a diagram to illustrate. Thk u tianzhu for the effort to come out with the 2nd solution (dividing the original triangle into 3 different triangles with height =r). Really thankful to both of you for your time and effort. I'm now able to accept this as a P6 maths qtn.

:thankyou:

[Shimmer]

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.

Hi kaisugrandmaster

May I know how you get
Eugene --> 8 units
Freddy --> 8 units + 200
George --> 6 units + 150

[Winx5015]

Thanks tianzhu

[MathIzzzFun]

Shimmer:

MathIzzzFun:

[quote=\"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.

Hi kaisugrandmaster

May I know how you get
Eugene --> 8 units
Freddy --> 8 units + 200
George --> 6 units + 150[/quote]Hi
you can also use 1 unit - but will have to manipulate fractions.

Eugene --> 1 unit
Freddy --> 1 unit + 200
George --> 3/4 unit+ 150

George lost 1/6 to Eugene, 1/6 --> 1/8 unit + 25

In the end:
Freddy --> 1 unit + 200
George --> 5/8 unit + 125
Eugene --> 9/8 unit + 25

9/8 unit + 25 = 5/8 unit + 125 + 320
1/8 unit --> 105
1 unit --> 840

cheers.

[Essential]

Hi Tianzhu, need to trouble u with this question. Jim spent $80 and saved the rest of his allowance . When he increased his expenditure by 13 percent , his savings decreased by 20 percent . Find the ratio of the amount he saved to his allowance at first .

[tianzhu]

Essential:

Hi Tianzhu, need to trouble u with this question. Jim spent $80 and saved the rest of his allowance . When he increased his expenditure by 13 percent , his savings decreased by 20 percent . Find the ratio of the amount he saved to his allowance at first .

Hi

Good Morning.

Amount spent ------ 80

% increase ------- 0.13*80 ------- 10.4

Increase in spending leads to decrease in savings

20% ------- 10.4

100% ------- 52 (savings@first)

Allowance@first ------- savings + spending -------- 52 + 80 ------- 132

ratio of the amount he saved to his allowance at first ------ 52/132 -------- 13/33

Best wishes

[tianzhu]

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.

Hi

Good Morning.

You may use MD or work using units.

Total height for 6 pupils -------- 170*6 -------- 1020

Average height ------ 1 box or 1 unit

Average height of the first 4 pupils ------- 1 unit + 15

15*4 -------- 60

1020 – 60 ------- 960

960/6 ------- 160 (average height for Agnes and Tony)

Total height for , Agnes and Tony ------- 160*2 ------- 320

320 – 25 ------- 295

295/2 ------- 147.5

147.5 + 25 ------- 172.5 (Agnes's actual height)

Best wishes

[Suz855]

Need help,


The difference between thrice my age 3 years later and thrice my age 3 years ago equals my present age. What is my present age?

Is the answer 6 or 18 or both acceptable. Thanks :oops:

[beanbear]

I need help with this sum. The answer given was 56.


The total number of boys was 100% more than the total number of girls in Class A and Class B. The ratio of the number of boys to the number of girls in Class A was 4:3 and the ratio of the number of boys to the number of girls in Class B was 6:1. If there were 8 more boys in Class A than in Class B, find the number of pupils in Class A.

[pixiedust]

Suz855:

Need help,


The difference between thrice my age 3 years later and thrice my age 3 years ago equals my present age. What is my present age?

Is the answer 6 or 18 or both acceptable. Thanks :oops:

I plucked in the answers to check. Answer is 18.

present age = 18
3 years later, age=18+3=21, thrice age=63
3 years ago, age=18-3=15,thrice age=45
difference=63-45=18 <right>

present age = 6
3 years later, age=6+3=9, thrice age=27
3 years ago, age=6-3=3,thrice age=9
difference=27-9=18 <wrong>