Q&A - PSLE Math

[Winx5015]

thanks tianzhu

[superksmum]

Hi Tianzhu,

Thank you.

[Michaelia0816]

Ok thanks for checking my answer, Tianzhu!!!

[Michaelia0816]

2632parent:

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

I bet you have written it wrongly as Devi is 20% more than Susan at first!
I will write the answer in next posts!

[Michaelia0816]

100%-40%=60%

Monday:
Devi got 60% of sweets at first.
Susan got 40% of sweets at first.
2/5 of 60% is 24%
60%-24%=36%
40%+24%=64%
64%-36%=28%
28%-112 sweets
1%-4 sweets
100%-400 sweets
The answer is 400 sweets.

[Michaelia0816]

Wish u good luck in find the answer :xedfingers:

[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?