Q&A - PSLE Math

[lizawa]

Chan09:

Some help on this:

Mr Tan saves 15% of his salary. His savings increased by $18 when his salary increases by 5%. what is his salary before the increase?
Ans:$2400

Before :
Savings : 15%; salary : 100%
After :
Salary : 105%
savings -> 15% x 105 = 15.75%
0.75% -> 18
(salary before increase) 100% -> 18/0.75 x 100 = 2400

[JadeDry]

Hello,


I would appreciate input on this question:

Simplify:

((3 X squared-Y cubed) / (8 Z-squared)) / ((9 Y-squared)/10Z)) x ((6 Y-squared- Z cubed) / 5X))

My answer is ((X-Y cubed- Z squared) /2 ) Is this correct?

Thanks in advance for your assistance.

[sleepyqueen]

JadeDry:

Hello,


I would appreciate input on this question:

Simplify:

((3 X squared-Y cubed) / (8 Z-squared)) / ((9 Y-squared)/10Z)) x ((6 Y-squared- Z cubed) / 5X))

My answer is ((X-Y cubed- Z squared) /2 ) Is this correct?

Thanks in advance for your assistance.

Yes this is what I get also, hope we are right.
answer: (xy3z2)/2

[linden2000]

Hi. For the Nanyang Pri School’s P6 CA1 paper 2 question 18 (last question of paper 2), does anyone have any idea what is the missing number in the following sentence?


"The total area of Triangle A and Triangle B is _______of the area of Triangle C."

Other than algebra, how would we solve this question?

Many thanks.

[whitety]

Hi, I need help to solve 2010 Rosyth CA1 Paper 2 qn 5.


Mrs Tan takes 15 mins to paint a wall and Mr Tan takes 10mins to paint the same wall. If both of them paint the wall together, how long will they take to paint the wall?

Many Thanks!

[speedmaths.012624com]

whitety:

Hi, I need help to solve 2010 Rosyth CA1 Paper 2 qn 5.


Mrs Tan takes 15 mins to paint a wall and Mr Tan takes 10mins to paint the same wall. If both of them paint the wall together, how long will they take to paint the wall?

Many Thanks!

You can solve this without using fractions in the working.

Use a common multiple of 15 and 10, say 30.

Mrs Tan takes 15 mins to paint a wall.
In 30 mins, Mrs Tan can paint 2 walls.
Mr Tan takes 10mins to paint the same wall.
In 30 mins, Mr Tan can paint 3 walls.

In 30 mins, Mrs Tan and Mr Tan can paint 2 + 3 = 5 walls.
Paint 5 walls in 30 mins
Paint 1 wall in 30/5 = 6 mins.

Pupils can learn to solve such problems in our Maths camps on 10 Dec and 17 Dec.
Please see:
http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=43&t=25433

Pupils can also learn to solve similar problems from this book \"Go For A-* Volume 2\", which is available from any Popular Book stores.

[whitety]

Hi,

Thank you for the solution and the recommendations. Unable to send my dd for the maths camp as we will be away during that period. Will take a look at the book in Popular bookstore.

Many Thanks!

[JE382]

Can anyone help answer these questions? I need the working as I don't understand the questions.


1) Roy, Sam and Ted had a sum of money. Roy had 80% of Sam's money. Sam had 60% of Ted's. After Roy gave $12 to Sam, he had 5/7 of what Sam had. How much more money did Ted have than Sam in the end?

2) Neil and Paul had different sums of money. If Neil spent $40 each week and Paul spent $80 each week, Neil would still have $1040 left when Paul spent all his money. If Neil spent $80 each week and Paul spent $40 each week, Neil would still have $320 left when Paul spent all his money. How much did Paul have at first?

3)Jerry bought four times as many pencils as notebooks and spent a total of $21.60. He spent $2,40 more on notebooks than the pencils. Given that a notebook costs $3.20 more than a pencil, find the cost of a pencil.

4) Ms Lee baked 24 more chocolate muffins than banana muffins. After she gave away 1/6 of the chocolate muffins and 3/8 of the banana muffins,she was left with 35 more chocolate muffins than banana muffins. How many chocolate muffins did she bake at first?

5) At first, Ravi had $200 more than Vincent. He gave 40% of his money to Vincent. Vincent then gave 25% of his money to Ravi. In the end, Vincent had $68 more than Ravi. How much did Vincent give Ravi?

:thankyou:

[JE382]

One more question :

In the figure that is not drawn to scale, ABCF is a rectangle. Find the area of the shaded parts.
http://i44.tinypic.com/10s9jfb.png\">

[tianzhu]

JE382:

5) At first, Ravi had $200 more than Vincent. He gave 40% of his money to Vincent. Vincent then gave 25% of his money to Ravi. In the end, Vincent had $68 more than Ravi. How much did Vincent give Ravi?

Hi

Good Morning.

I assume that calculators would be allowed for this question. You may draw MD to show the transactions or choose to work using units.

At first
Ravi ----- 20 units + 200
Vincent ------20 units

I use 20 units instead of 10 units to avoid working with decimals during future transfer.

Ravi gave 8 units + 80 to Vincent. He was left with 12 units + 120

Vincent now had 28 units + 80

Vincent then gave 25% of his money to Ravi.
25% ------- 7 units + 20

In the end
Ravi --------- 19 units + 140
Vincent ------- 21 units + 60

19 units + 140 + 68 ------ 21 units + 60
1 unit ----- 74

Vincent gave (7*74) + 20 or 538 to Ravi.

Best wishes