Sharmum:

Hi


Nid help with this question.

https://s18.postimg.org/wk1illivd/20161011_195351.jpg\">

:thankyou:

Hi. I can't see the picture clearly. Is it 63 and 72?

Factors of 63: 7x9
Factors of 72: 8x9
The common factor is 9. That means the common length of A and B is 9cm.

So breadths are 7cm and 8cm. Sum is 15cm, side of square C.

Area of C=15x15 =225 sq cm#

Perimeter = 15x4 + 9x2 = 78cm#

love1001:

Hi, can someone help me with this combination type question?


Alice, Ben, Cathy, Daniel and Elle are seated in a row.
Alice can sit either on the extreme left or right.
Cathy must sit in the center.
How many different sitting combinations can there be?

What is the easiest method to solve within the need to draw it out?

Can go by method of listing:
We commonly see similar question with 3 people (X Y and Z) and most P3 are taught to solve by listing.
XYZ XZY YXZ YZX ZXY ZYX (6 ways, \"basic\" list)

So for your question: we know C must be centre. A is either on extreme left or right.
Suppose A is on extreme left like this:
[A ? C ? ?]
Then remaining B, D and E have be like the above \"XYZ\" case, 6 ways to fill the remaining 3 seats.
*Notes (just for understanding):
BDE BED DBE DEB EBD EDB (just need to understand this basic list of 6 choices)
This arrangement is the same as below, since \"_\" are fixed positions taken up by A and C.
_B_DE / _B_ED / _D_BE / _D_EB / _E_BD / _E_DB (same basic list)

But A can also switch to the extreme right like this:
[? ? C ? A]
Then in the same way, there are another 6 ways to for B, D and E to fill the remaining 3 seats.
*Notes (not necessary to list again)
BD_E_ / BE_D_ / DB_E_ / DE_B_ / EB_D_ / ED_B_ (same basic list)

Total is 6+6=12 ways#

1010happy:

Dear parents,

my cousin's DD got CO from NYGH and R from RGS, but doesnt want to go there.... in fact she really very very very strongly loves RGS because of multiple reasons. She even is considering rejecting NYGH and trying for RGS. But she did quite terribly for prelim and is now really trying hard, should he let her go for it or try and persuade her to go the safer route by accepting NYGH? :?:

It is crucial not to be stressed out by this decision at this point, though easier said than done. If I'm not wrong, the DSA preference form submission is after all the PSLE exams. Just let the kid know that right now, she only needs to do her best for the exams and after that, have a self-assessment on how she think she has performed in the exams. Sometimes kids discussed answers after the exams and they may know how well they do. Having a good gauge of her actual performance will let her make a more informed decision, while weighing her risks at the same time. She can take all the time she needs to hear suggestions and think about what choices to make after the PSLE. So at the moment, just redirect all the attention to the exams. All the best for her.

sparkling_stars:

Chee Seng has a number of 10 cent, 20 cent and 50 cent coins in the ratio of 5:2:1. The total value of all the coins is $168. What is the total value of the 20 cent coins?


I just can't seem to think of the solution. Can you please send me the steps of how to do it to? Thanks a lot.

Should post in p6 Maths if administrator can help.
Hi, sparkling_stars,
1 set of coins is 5pc of 10cents, 2pc of 20cents and 1pc of 50cents = $1.40
There are 168/1.40 = 120 sets.
So there are 120 X 2pc = 240pc (of 20 cents)
Which is $48 of 20cents coins.

Check: 120 X 5pc = 600pc (of 10cent) is $60
120 X 1pc = 120pc (of 50cent) is $60
Total is $48+$60+$60 = $168.

taringal:

Hi,


Please help on this question. Thank you.

Patrick, Devi and Jiamin each have the same number of beads. How many beads must Devi give to Patrick and Jiamin so that Patrick has 20 beads more than Devi and Jiamin has 4 fewer beads than Patrick?

Hi, hope the below helps...
http://i68.tinypic.com/t8vz80.jpg\">

Augmum:

VitoRelax:

[quote=\"lee_yl\"]

It is unlikely that two T-score could be the same as the T-score for any subject is a function of the variance and mean of the cohort's raw scores in that subject. While the published T-score is rounded up, rumor has it that in MOE's database, the actual T-score is stored up to 13 decimal places. And it is based on this actual T-score that students are ranked for their school selection.

Even though it is unlikely but it is still possible.

if 2 students taking the same 4 subjects in PSLE and got the same raw marks for the 4 subjects, of course their pale T-score,.....

So, if they take same 4 subjects and got the same raw marks, their t-score will be identical up to even 100,000 decimal places !

Exactly...this has been in my thoughts all this while...

Since the SAME T- score formula applies to everyone ...n the SAME mean n std deviation apply to all pupils when the same subject is concerned,..it puzzled me as why is it not possible to have identical agg T- scores ??
It's Not, as if that Moe has diff sets of means or std deviation within the same subj for diff pupils...

Thus, based on the above... Regardless of how many decimal places behind ...
i choose to believe that there is the possibility of pupils having the same agg T- score ...[/quote]Hi, I may be wrong but just putting down what I used to learn in Maths probability:
Yes, each PSLE subject has its own mean and standard deviation applied to all students.
To get exactly same PSLE T-score to all the decimal places, two students need to have exactly same raw % score for each of the four subjects.
Not considering half marks (or quarter marks for languages' raw score in 100%), a child has 1/100 X 1/100 X 1/100 X 1/100 chance to get exactly the same marks for each of his 4 subjects like another child.
That is 1/100000000 chance. I would think this is rare considering our cohort of 40k.

To play with Mathematical Probability, consider half marks (and quarter marks for languages) possibilities out of 100% for each subject,
Probability of exactly same raw% for all 4 subjects is like this:
E X M X S X MT
=1/400 X 1/200 X 1/200 X 1/400
= 1/6400000000

Then not forgetting we each MT has its own mean and standard deviation....
That will also cause PSLE T -score be different if two children have the same raw %
One Chinese student's EMSC is 80,81,90,88
One Tamil student's EMST IS 80,81,90,88
Both will still have different t-score.

Makes sense?

snowball:

Linden had 29 more fifty-cent coins than ten-cent coins.

After he had used 37 fifty-cent coins, the value of the fifty-cent coins was $3.20 more than the value of the ten-cent coins.
How many fifty-cent coins and ten-cent coins did he have at first?

TIA

An alternative way: If we treat it like an IQ question. It might be easier going by analysis.
Say instead of removing 37 pcs of 50-cent coins, we will remove exactly the extra 29 pcs of 50-cent coins,
So that we know there are equal no. of 10-cent and 50-cent coins n the \"pot\".

This means we will add back 8pcs (=37-29) 50-cent coins
to the \"pot\", or $4 of 50-cent coins.

Diff in value is $3.20+$4=$7.20
For each set of 1pc 50-cent coin and 1pc 10-cent coin, diff in value=$0.40
So there are 18 sets (=$7.20/$0.40).

No. of coins at first = 2 x 18 + 29 = 65

MathIsAwesome:

I got 260 and missed RI COP by 1 mark. Is it advisable for me to appeal to RI as I have many certificates？

Hi, I think you should if they accept your appeal (Maybe independent schools have no restrictions on who can appeal). Nobody knows the outcome of appeal but I'm 100% sure that the chance is 0% if you do not submit appeal application. Good luck!

I’m guessing this situation to appeal only if above 2015 COP might be due to the likely upward shift in cutoff points across most schools. It has been discussed that 2015 EESIS cutoff (262) and top 10% cutoff (252) is higher when compared to 2014 cutoff (EESIS 258, 10% 249). So for example, RI 2015 COP is 256, we should expect to see its 2016 cutoff point around say 261. Students with score 256-261 are none the wiser when using that 2015 booklet would have applied to RI as first choice this year but unable to get in. Hence, leaving many students in this range to appeal and it makes more sense for schools to consider them ahead of students applying with a PSLE score of 255 or less. As we know, such a range of 3 points would have more than enough to go through due to the many decimal points each score has. It also easier to manage administratively.

PollutedS:

Hi everyone!


Why is (2/3x-2) - (1/ 2-3x) = (3/3x-2) [Note: They are all fractions]

Thank you! :?:

Doesn't look like psle question. Anyway....
(2/3x-2) + [1/-(2-3x)] = 2/3x-2 + 1/3x-2 = 3/3x-2
Might be MO kind but I'm not sure. Definitely not psle so no worries.