## Thursday, September 27, 2012

### P6 fractions (fr PSME Fractions pg 22)

Question states that Susan should be (Peter plus Drinks)x2/5.
What is shown in solution provided is Susan's mass = 2/5 of everything.
Click here to compare with the wrong solution provided in the answer key.

## Tuesday, September 25, 2012

### P6 circles, "find radius/ diagonal of rect" (fr Ryan c)

AC = BO (Diagonals of a rectangle are equal in length)
BO is effectively a radius = 3cm

### P6 numbers, "chairs" (fr Chong yang)

My solution:

* I shall call the visible "un-overlapped" part of a chair's leg a "leg stub" for ease of reference.

Note that when measured from floor to foot of 4th chair, we are measuring 3 leg stubs (1 fewer than the total no. of chairs stacked up)

3 leg stubs --> 37.2cm
1 leg stub --> 37.2cm / 3 = 12.4cm

With 10 chairs stacked in this manner, there are only 9 leg stubs (10-1=9)

9 leg stubs --> 12.4cm x 9 = 111.6cm
(or  just 37.2 x 3 = 111.6)

Therefore, the height of each chair is:
206.9 - 111.6 = 95.3 (cm)

Option: (2)

## Monday, September 24, 2012

### P6 rate (fr Chloe)

For clearer question and my solution, refer to

## Thursday, September 20, 2012

### P6 Volume ( fr Zhi xuan)

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Interestingly, in this question, it does not matter how big the base area of the containers are!
(I can prove this.  See * below or email me @ changchengliang@gmail.com and I will explain why.)
The length of time is entirely dependent on the height of the container alone.
Since it takes 1hr to fill Tank A, which is 10cm high,
Time taken to fill Tank B is also 1 hr.
Time taken to fill Tank C is 3 hrs.

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*
juz to make things clearer,  take a look at the following drawing:

Assuming that the tank on the left is having the same shape and volume as the tank on the right.  The only difference is that the one on the left is partitioned into many small cubicles.  Each cubicle has a base area of 1cm2.

Question: When the rain falls, on both "tanks", will the time to fill one tank to the brim be different from the time taken to fill the other tank?

I am sure you will conclude that the answer is no.  Hence, the time to fill any tank with rain is the height of the tank itself.