$10--(-u-)Jerico wrote:Hi, Can someone please help with this question ? Tks in adv !

$2---(-u-)(52)

10u -> 2(u+52)

10u -> 2u+104

8u-> 104

u-> 13

**Hence MP3 player cost $10x13 = $130**

Check: 2 x (13+52) = 2 x 65 = 130.

Academic support for Primary 6 and PSLE

Post
by **sushi88** » Mon Jul 20, 2015 1:42 am

$10--(-u-)Jerico wrote:Hi, Can someone please help with this question ? Tks in adv !

$2---(-u-)(52)

10u -> 2(u+52)

10u -> 2u+104

8u-> 104

u-> 13

Check: 2 x (13+52) = 2 x 65 = 130.

Post
by **Ender** » Mon Jul 20, 2015 8:44 am

I'm of the opinion that we should add on the vertical straight lines of the quadrants too for the perimeter,sushi88 wrote:This is essentially a large circle of radius 28 cm with 2 smaller circles inside it with radius 14cm.Jerico wrote:Hi, Can someone please help with this question ? Tks in adv !

Area of shaded area

= area of large circle - area of 2 small circles

= pi(28)(28) - 2pi(14)(14)

= pi(784-392)

= 392pi cm2

Perimeter of one shaded region

= Perimeter of quadrant + perimeter of semi-circle

= 2pi(28)/4 + 2pi(14)/2

= 28pi cm

Perimeter of 4 shaded region

= 4 x 28pi

= 112pi cm

Making the perimeter = 112pi + 112

Post
by **sushi88** » Mon Jul 20, 2015 9:06 am

Yes you are right, Ender!Ender wrote:

I'm of the opinion that we should add on the vertical straight lines of the quadrants too for the perimeter,

Making the perimeter = 112pi + 112

I broke down the barriers for area and forgot to put back the boundaries for perimeter.

Use abstract thinking and forget the eyes...

You are welcome, Jerico.

- alfretztay
- KiasuGrandMaster
**Posts:**1199**Joined:**Sun Sep 12,**Total Likes:**5

Post
by **alfretztay** » Mon Jul 20, 2015 10:10 am

You are most welcome, EC72; and I am glad that you are able to understand.EC72 wrote: very much alfretztay for your detailed explanation. Understand it more clearly now.

Post
by **EC72** » Mon Jul 20, 2015 6:11 pm

This year, there are 2300 pupils in Sentosa Primary School. Comparing to last year, there is a 25% increase in the number of boys and a 25% decrease in the number of girls. The total number of students this year has increased by 15%.

a) Find the total number of pupils in Sentosa Primary School last year. (Got the answer as 2000)

b) Find the number of boys in the school this year.

a) Find the total number of pupils in Sentosa Primary School last year. (Got the answer as 2000)

b) Find the number of boys in the school this year.

Post
by **EC72** » Mon Jul 20, 2015 6:36 pm

Mrs. Lim bought some white rice and some brown rice. She cooked an equal amount of white and brown rice. She had 3/4 of the white rice and 3/8 of the brown rice left. What fraction of the rice which Mrs. Lim bought was cooked?

Post
by **EC72** » Mon Jul 20, 2015 6:55 pm

Khalid has two rectangular boxes of different sizes. The length, breadth and height of the larger box are twice those of the smaller box.

He packed 24 identical cubes exactly into the smaller box. How many such cubes can be packed exactly into the larger box?

He packed 24 identical cubes exactly into the smaller box. How many such cubes can be packed exactly into the larger box?

Post
by **Ender** » Mon Jul 20, 2015 6:57 pm

Let last years number of boys be 4B and girls be 4GEC72 wrote:This year, there are 2300 pupils in Sentosa Primary School. Comparing to last year, there is a 25% increase in the number of boys and a 25% decrease in the number of girls. The total number of students this year has increased by 15%.

a) Find the total number of pupils in Sentosa Primary School last year. (Got the answer as 2000)

b) Find the number of boys in the school this year.

Last year number of pupils is 2300/1.15 =2000

4B + 4G = 2000 => 12B + 12G = 6000 --(1)

5B + 3G = 2300 => 20B + 12G = 9200 ---(2)

(2) - (1)

8B = 3200

B= 400

This year, boys = 5B= 2000

Post
by **EC72** » Mon Jul 20, 2015 7:03 pm

Ender wrote:Let last years number of boys be 4B and girls be 4GEC72 wrote:This year, there are 2300 pupils in Sentosa Primary School. Comparing to last year, there is a 25% increase in the number of boys and a 25% decrease in the number of girls. The total number of students this year has increased by 15%.

a) Find the total number of pupils in Sentosa Primary School last year. (Got the answer as 2000)

b) Find the number of boys in the school this year.

Last year number of pupils is 2300/1.15 =2000

4B + 4G = 2000 => 12B + 12G = 6000 --(1)

5B + 3G = 2300 => 20B + 12G = 9200 ---(2)

(2) - (1)

8B = 3200

B= 400

This year, boys = 5B= 2000

Ender!

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