Q&A - PSLE Math

[Michaelia0816]

A) 100%+20%=120%

120%=120/100
120/100x$1.50=$1.80
B) 100%-25%=75%
75%= 75/100
75/100x500=375
C) 375x$1.80=$675
Now using the in front information to do D. It would be much easy.
500x$1.50=$750
675/750x100%=90%
100%-90%=10%
Decrease.
D)

[Michaelia0816]

Would it be better to draw model for understanding!

[Andrew Lee]

tianzhu:

Andrew Lee:

Hello, can help me solve Q10
http://i41.tinypic.com/2lw2dn8.jpg\">

Hi

Good Morning.

An interesting question, from the image you posted, it doesn't look that it from a past year paper.Could you share with us where is it from?

Sometimes, questions on circles look intimidating at first glance.Try to reorganise into familiar looking shapes.

Join the point of intersections(outermost) of the 3 circles to form an equilateral triangle.Join the centepoints (ABC) of the circles to form a smaller equilateral triangle.Add in an identical circle to touch the centrepoints of the two circles (BC) if you think it'll help you to see better.

Do some cut and paste of areas formed by the small arcs and triangles and you'll see that the area of shaded portion is equal to the area of a semi circle of radius 7 cm.

Area of shaded region = 1/2*22/7*7*7 = 77 sq cm

Best wishes

Thank you so much :rahrah:

[2632parent]

Pls help!!!


On Sunday, Mrs Tan gave Devi and Susan some sweets. On Monday, Devi gave Susan 40% of her sweet. On Tuesday after Susan gave 2/5 of her sweets to Devi, both of them have the same number of sweets. If Susan had 112 sweets more than Devi at first,how many sweets did Devi have on Sunday?

[MathIzzzFun]

2632parent:

Pls help!!!


On Sunday, Mrs Tan gave Devi and Susan some sweets. On Monday, Devi gave Susan 40% of her sweet. On Tuesday after Susan gave 2/5 of her sweets to Devi, both of them have the same number of sweets. If Susan had 112 sweets more than Devi at first,how many sweets did Devi have on Sunday?

Hi

in the end,
Susan --> 9 units --> 3/5 of Susan's sweets
Devi --> 9 units
Before Susan gave 2/5 to Devi,
Susan --> 15 units
Devi --> 3 units --> 3/5 of Devi sweets
At first,
Susan --> 13 units
Devi --> 5 units
So, 8 units ---> 112, 1 unit --> 14
Devi's sweets on Sunday --> 5 x 14 = 70

cheers.

[Michaelia0816]

Ok I also ok! Wrong only thank!! Teaching me too!

[tianzhu]

Michaelia0816:

Would it be better to draw model for understanding!

Hi

Good Morning.

Are you a PSLE 2012 student?

If you're talking about the \"Cindy and Mary Q\", here's the MD.

Hope this helps.

Best wishes.

http://farm8.staticflickr.com/7063/6909440818_71f17bbdb8_z.jpg\">

[2632parent]

MatnIzzzFun thank u for the fast reply still trying to digest the solution

[Michaelia0816]

Of course, using elder account. free to use.

[Michaelia0816]

Question needed help again!

Germaine wants to line the base of her cupcake tin with baking paper. Her cupcake tin have a round base of radius 3.5cm. She has a rectangle piece of baking paper which is 14cm by 20cm. How many cupcakes tin bases can she cuts out with the minimum wastage?(take pi as 22/7)
I just only needs the final answer.