Tutor MathsGuru: Ask me for your burning Maths questions!

[Dharma]

Almighty:

Hi all,


Can anyone help on the following qts:
1)48% of the pupils go to school by car.50% of those who donot go to school by car are girls.\t\t\t\t
25% of those who go to school by car are boys. How many percent of the total number of boys\tin the school go to school by car?\t\t
\t\t\t\t\t
\t\t\t\t\t\t
My method:\t\t\t\t\t\t
\t\t\t\t\t
\t\t\t\t\t\t
Boys :Girls\t (Car ---48%) \tBoys : Girls (Not by car -----52%\t)\t\t
12% : 36% (by car) --------\t26% :26% (Not by car)\t\t

total number of boys in the school = 12 % + 26% = 38%\t\t\t\t\t\t
total number of boys in the school go to school by car\t\t\t\t\t\t= 12% / 38% X 100
\t\t\t\t\t\t= 31 11/19%

Book answer = 12%\t\t\t\t\t\t
Can anyone clarify how can it just be 12%\t\t\t\t\t\t

2)The ratio of number of cars to the number of avns sold in a certain country\t\t\t\t\t\t
was 3:2 last year. This year. A total of 9600 more vans and cars are sold and there are twice as many vans and thrice as many cars as last year.How many cars are sold this year? \t\t

\t\t\t\t\t\t
Last year - cars sold\tThis year cars sold\t\t
C : V : Total\t\tC : V : Total\t\t
3 : 2 : 5\t\t\t 9 : 4 : 13\t\t
\t\t\t\t\t\t
\t8 units = 9600\t\t\t\t\t
\t1 unit = 1200\t\t\t\t\t
\t
So, we must find for 9 units to find the number of cars sold this year.\t
\t
ie., 9 units = 10800 carsBook method\t

6 units ( 9 - 3) ----- ? 1200 X 6\t
\t = 7200 cars
Can anyone clarify why should we do 9 - 3 ???\t


3)In a ballot school, 60% of the pupils are girls and the rest are boys.
How many percent more girls than boys are there in the ballet school?\t
\t
Girls ---60% \tBoys ----40%
\t\t\t
My method : ans : 50%\t
\t\t\t
\t20 / 40 X 100% = 50%\t\t
Work backwards:\t\t\t
50% X 40% = 20% ie , 40% + 20% = 60% \t\t\t
\t\t\t
Book method:\t\t\t
\t\t\t
Ans : 20% ie 60 % - 40%\t\t\t
\t\t\t
Work backwards:\t\t\t
20% X 40% = 8% ie., 40% + 8% = 48% not equal to 60%\t
\t\t\t
\t\t\t
My method: interpretating the question as:
How many percent more girls than boys are there in the ballet school

Book method : interpretating the question as
How many percent more girls are there than boys in the ballet school

Which is right??Can anyone please clarify on this?? :?:

Q1)


http://www.postimage.org/image.php?v=TsfKTo0


Q2)

Last year
Cars : 3u
Vans : 2u

This year
Cars : 9u
Vans : 4u

13u – 5u = 8u = 9600
1u = 1200

No. of cars sold this year = 9u = 9 x 1200 = 10800


Q3)

Your method is correct

[Dharma]

Almighty:

Hi again,

One more question:
http://www.postimage.org/image.php?v=TsdBLer
a) got the answer : 180Cm
For b)
My MEthod
FOr 1 glued plank ---210 cm
For 48 planks---? ie., 10080 cm

Each plank ----450 cm
?-----------10 080 cm
22.4 = 23 planks

Book method:
FOr 1 glued plank ---210 cm
for 450 cm --- 210 cm + 210 cm
No of wood needed ---- 48 /2 = 24 pieces
Am i right? If not, can anyone Please explain the book answer for (B)

1/3 of Y = ¼ of X
3u = 90cm
1u = 30cm

a)\t1 set of glued plank X + Y = 90 + 120 – 30 = 180cm
b)\tTo make 1 glued plank, Mr Tan needs 120cm length of X + 90cm length of Y
To make 1 set he needs 210cm length of plank.
1 length of plank = 4.5m = 450cm
450cm/210cm = 2.14 ( he gets 2 sets of glued plank)
So, from 1 length of plank (450cm), Mr Tan is able to make 2 pieces of glued plank.

If Mr Tan needs 48 pieces of glued plank; he needs to buy 48/2 = 24 pieces of 4.5m length plank.

[tianzhu]

Hi

Hope this helps.
Best wishes.

http://farm5.static.flickr.com/4079/4878572580_8151c55d50_b.jpg\">

[Muffins]

Hi Tianzhu, by the way, I found these pictures... They are originally from fotolia....

[Kiasu Friend]

Muffins:

Hi Tianzhu, by the way, I found these pictures... They are originally from fotolia....

Hi Muffins,

I had requested some info from you under the thread on - 'Anglo-Chinese (Independent) IP'. When you can spare time, please visit the thread at -
http://www.kiasuparents.com/kiasu/forum/viewtopic.php?p=230335#230335 and kindly reply to my queries.

Thank you very much for your time.

[Dharma]

OngMum:

I have two questions that need guidance :-


1. Edison cycled at a speed of 10m/min while Damien cycled at a speed of 15m/min. Edison started cycling from Sleepy Town and Damien started at the same time from Happy Town. They cycled towards each other. They first met at Point Q and then continued to cycle. Upon reaching their destination, they made a U-turn and continued cycling towards each other again. This time, they met at Point R. The distance between Point Q and Point R was 324m.

(a) What was the distance between Sleepy Town and Happy Town?
(b) How long would Edison have cycled when he met Damien at Point R?


2. 2 identical tins, X and Y, were half filled with paint. Tin X contained only white paint while Tin Y contained only black paint. 1/2 of the white paint in Tin X was poured into Tin Y. After stirring the contents in Tin Y thoroughly, 1/2 of the mixed paint in Tin Y was poured into Tin X. The contents in Tin X ws mixed thoroughly and 1/2 of the mixture was then poured into Tin Y. If 7.2 litres of black paint was in the mixture in Tin X, how much white paint would there be in the mixture in Tin X?

Thank you. Cheers!

Q1)
Time is constant - when Edison met Damien
Speed ratio => Edison : Damien = 2 : 3
Distance ratio => Edison : Damien = 2 : 3

When Edison met Damien at Point Q, Edison travelled a distance of 2u while Damien travelled a distance of 3u.
So, the distance between Sleepy Town and Happy Town is 5u.
When Edison and Damien met for the next time at Point R; Edison travelled a distance of 4u while Damien travelled a distance of 6u.

a) Distance between Point Q and R = 2u
2u = 324m

Distance between Sleepy Town and Happy Town = 5u = ( 324/2 x 5 ) = 810m

Q2)
At first
Tin X : 100u
Tin Y : 100p

½ of white paint in Tin X poured into Tin Y
Tin X : 100u – 50u = 50u
Tin Y : 100p + 50u

½ of mixture in Tin Y poured into Tin X
Tin X : 50u + ( 50p + 25u) = 75u + 50p
Tin Y : 50p + 25u


½ of mixture in Tin X poured into Tin Y
Tin X : 37.5u + 25p
Tin Y : ( 50p + 25u ) + 37.5u + 25p = 62.5u + 75p

Tin Y => 25p = 7.2l
Amt of black paint at first =100p = 28.8l

Amt of white paint at first =100u = 28.8l
Amt of white paint left in Tin X = 37.5u = 10.8l

[Yu Xuan]

maths6a:

http://www.postimage.org/image.php?v=TsdpVqJ





In the figure, KE = EL, AE = ED and BC is 3 times KB. Area of rect ABCD is 94 cm2 and the area of triangle KGB is 6 cm2.
Find the area of triangle KEL.

Thx for the tips. With some trial and error finally got it up. Please let me know what you think of this question. Thanks. :?

I got 77cm2 while my son got 78 1/3 cm2 through a different method.

My method;

Rect GBCH is made up of 6 KGB --> 6 * 6 = 36
Hence AGDE --> 94 - 36 = 58
EGH is half of AGDE --> 58 / 2 = 29
Triangle KEL --> 29 + 36 + 6 + 6 = 77

My son's method;

CD --> 94 / 3 units
Area of KEL --> 1/2 * 94/3u * 5u = 78 1/3

Is any of our answer right? :?

[Dharma]

maths6a:

http://www.postimage.org/image.php?v=TsdpVqJ





In the figure, KE = EL, AE = ED and BC is 3 times KB. Area of rect ABCD is 94 cm2 and the area of triangle KGB is 6 cm2.
Find the area of triangle KEL.

Thx for the tips. With some trial and error finally got it up. Please let me know what you think of this question. Thanks. :?

http://www.postimage.org/image.php?v=PqLd5uS

[Almighty]

Dharma:

Almighty:

Hi all,


Can anyone help on the following qts:
1)48% of the pupils go to school by car.50% of those who donot go to school by car are girls.\t\t\t\t
25% of those who go to school by car are boys. How many percent of the total number of boys\tin the school go to school by car?\t\t
\t\t\t\t\t
\t\t\t\t\t\t
My method:\t\t\t\t\t\t
\t\t\t\t\t
\t\t\t\t\t\t
Boys :Girls\t (Car ---48%) \tBoys : Girls (Not by car -----52%\t)\t\t
12% : 36% (by car) --------\t26% :26% (Not by car)\t\t

total number of boys in the school = 12 % + 26% = 38%\t\t\t\t\t\t
total number of boys in the school go to school by car\t\t\t\t\t\t= 12% / 38% X 100
\t\t\t\t\t\t= 31 11/19%

Book answer = 12%\t\t\t\t\t\t
Can anyone clarify how can it just be 12%\t\t\t\t\t\t

2)The ratio of number of cars to the number of vans sold in a certain country\t\t\t\t\t\t
was 3:2 last year. This year. A total of 9600 more vans and cars are sold and there are twice as many vans and thrice as many cars as last year.How many cars are sold this year? \t\t

\t\t\t\t\t\t
Last year - cars sold\tThis year cars sold\t\t
C : V : Total\t\tC : V : Total\t\t
3 : 2 : 5\t\t\t 9 : 4 : 13\t\t
\t\t\t\t\t\t
\t8 units = 9600\t\t\t\t\t
\t1 unit = 1200\t\t\t\t\t
\t
So, we must find for 9 units to find the number of cars sold this year.\t
\t
ie., 9 units = 10800 cars My answer(forgot to write this?)
Book method\t

6 units ( 9 - 3) ----- ? 1200 X 6\t
\t = 7200 cars
Can anyone clarify why should we do 9 - 3 ???\t


3)In a ballot school, 60% of the pupils are girls and the rest are boys.
How many percent more girls than boys are there in the ballet school?\t
\t
Girls ---60% \tBoys ----40%
\t\t\t
My method : ans : 50%\t
\t\t\t
\t20 / 40 X 100% = 50%\t\t
Work backwards:\t\t\t
50% X 40% = 20% ie , 40% + 20% = 60% \t\t\t
\t\t\t
Book method:\t\t\t
\t\t\t
Ans : 20% ie 60 % - 40%\t\t\t
\t\t\t
Work backwards:\t\t\t
20% X 40% = 8% ie., 40% + 8% = 48% not equal to 60%\t
\t\t\t
\t\t\t
My method: interpretating the question as:
How many percent more girls than boys are there in the ballet school

Book method : interpretating the question as
How many percent more girls are there than boys in the ballet school

Which is right??Can anyone please clarify on this?? :?:

Q1)


http://www.postimage.org/image.php?v=TsfKTo0


Q2)

Last year
Cars : 3u
Vans : 2u

This year
Cars : 9u
Vans : 4u

13u – 5u = 8u = 9600
1u = 1200

No. of cars sold this year = 9u = 9 x 1200 = 10800


Q3)

Your method is correct

Hi Dharma Sir,

There was a spacing mistake (as indicated in violet) for qt 2.
According to your answer, i think i have got qt 2 n 3 right .
Will go thru yr working for qt 1.

Thankyou very much for the effort taken by you to clarify my doubts.
Thankyou others too...

[Almighty]

Dharma:

Almighty:

Hi again,

One more question:
http://www.postimage.org/image.php?v=TsdBLer
a) got the answer : 180Cm
For b)
My MEthod
FOr 1 glued plank ---210 cm
For 48 planks---? ie., 10080 cm

Each plank ----450 cm
?-----------10 080 cm
22.4 = 23 planks

Book method:
FOr 1 glued plank ---210 cm
for 450 cm --- 210 cm + 210 cm
No of wood needed ---- 48 /2 = 24 pieces
Am i right? If not, can anyone Please explain the book answer for (B)

1/3 of Y = ¼ of X
3u = 90cm
1u = 30cm

a)\t1 set of glued plank X + Y = 90 + 120 – 30 = 180cm
b)\tTo make 1 glued plank, Mr Tan needs 120cm length of X + 90cm length of Y
To make 1 set he needs 210cm length of plank.
1 length of plank = 4.5m = 450cm
450cm/210cm = 2.14 ( he gets 2 sets of glued plank)
So, from 1 length of plank (450cm), Mr Tan is able to make 2 pieces of glued plank.

If Mr Tan needs 48 pieces of glued plank; he needs to buy 48/2 = 24 pieces of 4.5m length plank.

Hearty thanks once again Dharma Sir. WIll go through your working..and i know u will be there to clarify my further querries (in case i have any)