Q&A - PSLE Math

[zanen]

mind helping wif this question? Tong Ming and Wei De bought 2 fruits, apples and oranges, from a fruit stall. Altogether, they bought 30 more apples than orange. Tong Ming bought 2/5 of the total number of fruits. Wei De bought 2/3 of the apples ajnd 1/2 of the orange. How many fruits did they buy altogether?

[Zhu99]

zanen:

mind helping wif this question? Tong Ming and Wei De bought 2 fruits, apples and oranges, from a fruit stall. Altogether, they bought 30 more apples than orange. Tong Ming bought 2/5 of the total number of fruits. Wei De bought 2/3 of the apples ajnd 1/2 of the orange. How many fruits did they buy altogether?

u --- apple, p --- orange

Wei De ---- 2 u + 1 p ----- 1 - 2/5 = 3/5
Tong Ming ---- 1 u + 1 p ---- 2/5

From above 1 u = 1 p

3 u - 2 p = 3 u - 2 u = 1 u ---> 30

5 u ---> 5 x 30 = 150

They bought 150 fruits altogether.

[ksme]

kuts:

Can anyone help me to solve the qn no. 29 of Tao Nan 2012 Prelims.


Thanks in advance

Hi,
Is this the ribbon question? If yes, here's the solution:

Vertical sides = 4*22cm = 88cm
top and bottom sides =2*(15+20)=70cm
Ribbon used to tie the bow = 200-88-70=42cm
Answer = 0.42m

[ms_lim]

tianzhu:

ms_lim:

Can help to explain how to solve this question?


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Hi

Where is this question from?

I don’t have the Casio calculator, so using 3.142 for pi.

Area for the left figure ------ area of two circles of radius 10cm

Area for the left figure ------ 2 * 3.142* 10*10 -------- 628.4

The right figure also has the same area.

Best wishes

Dear tianzhu,
Thanks. This qn is from Nanyang Prelim 2012. It took a while for ds to figure out.

[ms_lim]

charsen:

ms_lim:

Can help to explain how to solve this question?


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C)
I try to find the general rule and i found it for how to find the total no.of tiles.It is (pattern no.x2-1)x(pattern no.x2-1)+4.
I subtracted 4 from the total no. of tiles in each question.For example,29-4=25.
You know that 25 is a square root of 5,which is a odd no.So,if you subtract 4 from all the total no. of tiles,you get the square root of odd no.Next,you should find the odd no. of the square root you found.
take pattern 3 as an example.

29-4=25
5x5=25
i need to find the relation ship between the pattern no. and the odd no.So,I used the formula to find odd numbers which is 2n-1-->(3+3)-1=5
And there,i found the formula.
Cheers

Thanks charsen for the detail explanation.

[tianzhu]

Michaelia0816:

I want you to help me part (a) with the speed question as I dun understand and for the Ali question, which give me the answer, ( for checking)

Hi girl

For Ali question,the answer is 775.

To make it more convenient for you to read, I'll also repost the answer on Speed posted this morning.

Best wishes.

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[Winx5015]

Thanks charsen and tianzhu for your help As for question 1, already check with the teacher, it is an invalid question, so just ignore it. Thanks.

[Winx5015]

Wendy has 80 more stamps than Mary but 50 more stamps than Jean. Wendy gives 1/2 of her stamps to Mary. Then Mary gives 1/5 of her stamps to Jean. If Jean has 62 more stamps than Wendy, how may stamps does Mary have in the end?


(Can tell me how to solve this question? Thanks)

[tianzhu]

kuts:

Help please.... from Tao Nan Prelims 2012


1. There was some water in a container. Felicia first poured out 1/2 of the water. The she poured out 1/3 of the remaining water. In the third pouring, she poured ouot 1/4 of the remaining water and so on. How many times pouring will there be for the remaining water to be exactly, 1/10 of the original amount of water in the container?


Thanks in advance!

Hi

Try to see the pattern of 1/(n+1) for the remaining amount of water, where n refers to the number of pourings

In this case, it’s the 9th pouring.

Best wishes

[tianzhu]

Winx5015:

Wendy has 80 more stamps than Mary but 50 more stamps than Jean. Wendy gives 1/2 of her stamps to Mary. Then Mary gives 1/5 of her stamps to Jean. If Jean has 62 more stamps than Wendy, how may stamps does Mary have in the end?


(Can tell me how to solve this question? Thanks)

Hi

You may use MD or units.

At first

Mary ------ 10 units

Wendy ------ 10 units + 80

Jean ------ 10 units + 30

Wendy gives 1/2 of her stamps to Mary.

Wendy

Left ------ 5 units + 40

Gave ------ 5 units + 40

Mary ------- 15 units + 40

Then Mary gives 1/5 of her stamps to Jean.

Mary

Left ------ 12 units + 32

Gave ------ 3 units + 8

Jean ------ 13 units + 38

If Jean has 62 more stamps than Wendy, how may stamps does Mary have in the end?

13 units + 38 ------ 5 units + 40 + 62

8 units ------- 64

1 unit ------ 8

Mary ------ 12 units + 32 ------- 128

Best wishes