Tutor MathsGuru: Ask me for your burning Maths questions!

[Vanilla Cake]

ck123:

Anyone tried 2009 SCGS SA2 paper 1 Q28?


Question is:

The following figure shows a square piece of cardboard WXYZ. Four small squares of equal size and a circle, twice the area of each small square, were cut out from the cardboard. What percentage of the cardboard was cut out?
sorry but i don't know how to insert the diagram. Anyone came across this question? Please help :?:
Thanks

http://www.orlesson.org/orp/09Ma/2009-Math-SA2-SCGS.pdf
Assume side of 1 small square to be 1 unit
Side of the cardboard WXYZ will be 4 units for WX, XY, ZY and WZ.
Area of cardboard = 4 units x 4 units = 16 units²
Area of 4 small squares = 4 x 1 unit x x 1 unit = 4 units²
Since area of a circle = twice of area of each small square -> area of circle = 2x 1 unit x 1 unit = 2 units²
Total area that were cut out from the cardboard -> 4 smalls squares + 1 circle = (4+2) units² = 6 units²
6 units²/16 units²x100% = 37.5%
Percentage of the cardboard that was cut out = 37.5%.

[CJM]

1 Carton of marbles and 1/4 carton of golf balls cost $150.

3 Cartons of marbles and 11/16 carton of golf balls cost $130.

How much is the cost of 1 1/2 carton of golf balls ?

[CJM]

There are some coins in a box made up of 20-cent and $1 coins. There are thrice as many 20-cent coins as $1 coins. If the total amount of money in the box is $48, how many coins are there altogether ?

[iFruit]

CJM:

1 Carton of marbles and 1/4 carton of golf balls cost $150.

3 Cartons of marbles and 11/16 carton of golf balls cost $130.

How much is the cost of 1 1/2 carton of golf balls ?

1M + 1/4 G = 150

so,

3M + 3/4G = 450------->(1)

we also have

3M + 11/16G = 130 ------>(2)

From (1) and (2)

3/4G - 11/16G = 320

1/16 G = 320

3/2 G = 24/16G = 24x320 = $7680

That means you can get rich just by buying marbles

There is probably a typo somewhere in the problem.

[iFruit]

CJM:

There are some coins in a box made up of 20-cent and $1 coins. There are thrice as many 20-cent coins as $1 coins. If the total amount of money in the box is $48, how many coins are there altogether ?

Let number of $1 coins = u
Number of 20-cent coins = 3u

value of coins = u+0.2(3u) = 1.6u = 48

u = 48/1.6 = 30

Total coins = 4u = 120

HTH

[Jan111]

Hi,

I have a question on P5 Maths, really do not know how to do. Thanks in advance for helping.

Francis,Gif and Hakim shared a sum of money.Hakim decided to give Francis 2/3 of his money.Then, Francis gave Gif 3/4 of his money and Gif gave 3/7 of his money to Hakim. In the end, the amount of money they had was in the ratio 3:6:8. If Hakim had $55 more than Francis at first, how much money did Gif have in the end?


Thanks.

[atutor2001]

Jan111:

Hi,

I have a question on P5 Maths, really do not know how to do. Thanks in advance for helping.

Francis,Gif and Hakim shared a sum of money.Hakim decided to give Francis 2/3 of his money.Then, Francis gave Gif 3/4 of his money and Gif gave 3/7 of his money to Hakim. In the end, the amount of money they had was in the ratio 3:6:8. If Hakim had $55 more than Francis at first, how much money did Gif have in the end?


Thanks.

Hi is the answer $15 for Gif

I used \"unit\" method and worked backward and obtained the ratio at first to be :

F : G : H = 10 : 3 : 21


Hope some one can help to post the flow on how to convert to the same unit by working backwards.
I am zero when it comes to posting picture. Very sorry.

PS
Sorry, $15 if for Gif (at first) didn't read question. Careless as ever, sure die if I take PSLE now.

[iFruit]

atutor2001:

Jan111:

Hi,

I have a question on P5 Maths, really do not know how to do. Thanks in advance for helping.

Francis,Gif and Hakim shared a sum of money.Hakim decided to give Francis 2/3 of his money.Then, Francis gave Gif 3/4 of his money and Gif gave 3/7 of his money to Hakim. In the end, the amount of money they had was in the ratio 3:6:8. If Hakim had $55 more than Francis at first, how much money did Gif have in the end?


Thanks.

Hi is the answer $15 for Gif

I used \"unit\" method and worked backward and obtained the ratio at first to be :

F : G : H = 10 : 3 : 21


Hope some one can help to post the flow on how to convert to the same unit by working backwards.
I am zero when it comes to posting picture. Very sorry.

Sorry about the picture too..but here is the working.

At the End
-------------
Francis = 3u
Gif = 6u
Hakim = 8u

1 step back
------------
Francis = 3u
Gif = 7/4x6u = 21u/2
Hakim = 8u – 21u/2 x 3/7 =7u/2

2 steps back
-------------
Francis = 4 x 3u = 12u
Gif = 21u/2 – 9u = 3u/2
Hakim = 7u/2

3 steps back
-------------
Francis = 12 – (21u/2 x 2/3 ) = 5u = 10u/2
Gif = = 3u/2
Hakim = 7u/2 x 3 = 21u/2

21u/2 - 10u/2 = 55 ----> u = 10

Gif at the end = 6u = 6x10 = 60


Easier to understand this if drawn in a table..

HTH

[Vanilla Cake]

firebird:

1) John had $180 more than Raymond at first. Both bought a different printer with some of their money. In the end Rayamond was left with $20 more than John. If John's printer cost 50% more than Raymond's printer, how much does John's printer cost?

This question is from Catholic High School (Primary) 2010 P6 Prelim Paper 2 Q11 [3 marks]

John had $180 more than Raymond at first. Both bought a different printer with some of their money. In the end, Raymond was left with $20 more than John. If John's printer cost 50% more than Raymond's printer, how much does John's printer cost?

firebird:

2) At 9am John was cycling from Point A to Point B. At the same time, Mary was cycling from point B to point A using the same route as John. Cycliing at a speed of 4km/h faster than Mary, they would pass each other 300 meter away from the mid point.
a) What time did they pass each other?
b) If John took another 3 minutes to reach Point B, what time would Mary reach Poin A?

This question is from Catholic High School (Primary) 2010 P6 Prelim Paper 2 Q15 [5 marks]

At 9 a.m., John was cycling from Point A to Point B. At the same time, Mary was cycling from Point B to Point A using the same route as John. Cycling at a speed of 4km/h faster than Mary, John would pass Mary 300m away from the midpoint.
a) What time did they pass each other?
b) If John took another 3 minutes to reach Point B, what time would Mary reach Point A?

firebird:

3) Daniel had 40% more stickers than Brandon. Daniel and Brandon each gave 20% of their stickers to Calvin. As a result, Calvin's stickers increased by 80%. If Daniel has 20 more stickers than Calvin in the end, how many stickers did Brandon have at first?

This question is from Catholic High School (Primary) 2010 P6 Prelim Paper 2 Q17 [5 marks]

firebird:

4) At a conference made up of speakers and participants, there were 20% more men than women. The ratio of male speakers to female speakers was 8:5. There was an equal number of male and female participants.
a) Find the ratio of male speakers to male participants at the conference.
b) Halfway, 40 male participants left the conference and another 60 female participants joined the conference. In the end, there were 3/4 as many male participants remaining behind. How many speakers were there at the conference?

This question is from Catholic High School (Primary) 2010 P6 Prelim Paper 2 Q18 [5 marks]

At a conference made up of speakers and participants, there were 20% more men than women. The ratio of male speakers to female speakers was 8:5. There was an equal number of male and female participants.
a) Find the ratio of male speakers to male participants at the conference.
b) Halfway, 40 male participants left the conference and another 60 female participants joined the conference. In the end, there were 3/4 as many male participants as female participants remaining behind. How many speakers were there at the conference?

This post is made to reflect the original questions and its source for reference purpose. Solutions for the above questions by Uncle Dharma can be found http://www.kiasuparents.com/kiasu/forum/viewtopic.php?t=6373&postdays=0&postorder=asc&start=2510.

[CJM]

iFruit:

CJM:

There are some coins in a box made up of 20-cent and $1 coins. There are thrice as many 20-cent coins as $1 coins. If the total amount of money in the box is $48, how many coins are there altogether ?

Let number of $1 coins = u
Number of 20-cent coins = 3u

value of coins = u+0.2(3u) = 1.6u = 48

u = 48/1.6 = 30

Total coins = 4u = 120

HTH

thank u