Q&A - PSLE Math

[tianzhu]

pixiedust:

For unitary method, I can get the right answer but I can't explain how to handle the $9.

Hi pixiedust

Good Morning.

I am wondering what you mean by using unitary method.

The unitary method involves the finding of a value equivalent to one unit. Then use this value to find the value of more units. In a way, the working in MD is quite similar; we are also using the unitary method.

An example of using unitary method.

110% of Science score ------ 88
1% of Science score ----- 88/110
100% of Science score ----- 88/110*100 ----- 80

110 units ------ 88
1 unit ------ 88/110
100 units ----- 88/110*100 ------ 80

Best wishes

[mumworks]

Hi,


Besides using guess and check, any better way to solve this problem ?

360 teachers and pupils participated in tree planting.
Each teacher planted 3 trees and each group of 3 pupils planted 2 trees.
If 520 trees were planted altogether, how many pupils were there ?

Thanks in advance.

[sweetcandy]

mumworks:

Hi,


Besides using guess and check, any better way to solve this problem ?

360 teachers and pupils participated in tree planting.
Each teacher planted 3 trees and each group of 3 pupils planted 2 trees.
If 520 trees were planted altogether, how many pupils were there ?

Thanks in advance.

Hi,

I am not sure if I am right but we can use equation:

360 = T + S (T-teachers and S-Student)
520 = 3T+2S/3 (Total numbers of trees)
.
....

You will get S= 240 (there are 240 students)

Check answer:
240 (students) + 120 Teachers = 360
(240/3)2+(3*120) = 520 trees

So I am not guessing my answer right?

[tianzhu]

mumworks:

Hi,


Besides using guess and check, any better way to solve this problem ?

360 teachers and pupils participated in tree planting.
Each teacher planted 3 trees and each group of 3 pupils planted 2 trees.
If 520 trees were planted altogether, how many pupils were there ?

Thanks in advance.

Hi

You may use \"Make a Supposition\"

This solution for a similar type of question may help.

The answer to your question is 240 pupils (120 teachers)

Best wishes

http://farm8.staticflickr.com/7022/6518324819_548ca9d2dc_z.jpg\">

[homeworkmummy]

Hi, pls help with the following question and thanks in advance.


Yvonne had 20% less beads than Pris. Jess had 20% more beads than Yvonne. Express Jess’s beads as a percentage of Pris’s beads.

I was told that Yvonne -> 120%. Could someone pls tell me why is that so?

[tianzhu]

homeworkmummy:

Hi, pls help with the following question and thanks in advance.


Yvonne had 20% less beads than Pris. Jess had 20% more beads than Yvonne. Express Jess's beads as a percentage of Pris's beads.

I was told that Yvonne -> 120%. Could someone pls tell me why is that so?

Hi

You may choose to work using percentages or units.

Pris ------ Base Percentage ------ 100% ------- 100 units

Yvonne ----- (20% less beads than Pris) ------ 80% ------ 80 units

Jess ----- (20% more beads than Yvonne) ------ 120%*80% ------ 96% ------ 96 units

Jess's beads as a percentage of Pris's beads -----96%

Best wishes

[Winx5015]

Hi,


Can help me solve this question.

Jenny and Tom had $380 altogether. Jenny spent 5/6 of her money and Tom Spent 3/4 of his money. In the end, both of them had $80 left altogether. How much money did Jenny have at first?

Thanks!

[tianzhu]

Winx5015:

Hi,


Can help me solve this question.

Jenny and Tom had $380 altogether. Jenny spent 5/6 of her money and Tom Spent 3/4 of his money. In the end, both of them had $80 left altogether. How much money did Jenny have at first?

Thanks!

Hi

This question touches on simultaneous concept.

You may use Units and Parts, letters of the alphabet or solve it the pictorial way.

Please refer to some of the earlier posts for examples of such solution.

I’ll use the alphabet way.

Jenny
Spent ----- JJJJJ
Left ----- J

Tom
Spent ----- TTT
Left ----- T

Both of them had $80 left altogether.
J + T ----- 80

JJJJJ + TTT ----- 300 (380-80)
JJ + 240 ----- 300
JJ ----- 60

J ----- 30

Jenny ----- JJJJJJ ------- 180 at first.

Best wishes

[Winx5015]

Hi tianzhu,


Thanks for saving my day.

Enjoy your weekends :thankyou:

[Chan09]

Q7. I have some red & blue ribbons in a bottle. If I add in 20 red ribbons, 60% of my ribbons are blue. If I add in another 60 blue ribbons, 75% of my ribbons are blue. How many ribbons have I in the bottle ??


Ans: 180 but I don’t understand why deduct 20 red if I use the UTM method, can this be done by model? As I got 160 if I use model?