Tutor MathsGuru: Ask me for your burning Maths questions!

[clblinym]

Dharma:

Q19


When Betty and David at Pt C, they walked 1/2 the circumference in total. When they meet for the 2nd at Pt D, they walked the circumference in total ( from Pt C to Pt D)

AC = 80m
BD = 60m

2 x AC = CB + BD
CB = 160m - 60m = 100m

Circumference = (60m + 100m) x 2 = 360m

Dear Dhrma,
I still can't figure out how you get
2 x AC = CB + BD. Can you explain? Thanks

Thanks,
Amy

[john69888]

Dear All,


How to print the JPG file math guru posted on Kiasuparents? I download the jpg files and print the files, but it is NOT clear.

Pls kindly tell how to print the JPG file math guru posted on Kiasuparents.

Thanks,

Liew

mathsguru:

suiyuan:

1)During a warehouse book sale, Sally spent 62.5% of her money on 24 books and 18 pens. She also spent 25% of her remaining money on 18 files. Each pen costs 8/9 as much as the price of one book. The file costs $7.80 less than a book. Find the total cost of one book and one pen.

Hi Suiyuan,

Please see my solution and explanation in the attached picture.

http://www.postimage.org/image.php?v=aV1esa5S

Cheers,
MathsGuru

[Dharma]

clblinym:

Dharma:

Q19


When Betty and David at Pt C, they walked 1/2 the circumference in total. When they meet for the 2nd at Pt D, they walked the circumference in total ( from Pt C to Pt D)

AC = 80m
BD = 60m

2 x AC = CB + BD
CB = 160m - 60m = 100m

Circumference = (60m + 100m) x 2 = 360m

Dear Dhrma,
I still can't figure out how you get
2 x AC = CB + BD. Can you explain? Thanks

Thanks,
Amy

Hi Amy,

Both Betty and David walk at constant speed.
When they meet at Point C, notice that in total both of them covered a distance of 1/2 the circumference of the circle.

Then from Point C to Point, in total both them covered a distance that is equal to the circumference of the circle.

Distance covered by Betty from Point A to Point C when she first met David = AC.

Distance covered by Betty from Point C to Point D when she met David again = CB + BD

Since her walking speed is constant, she had to walk twice the distance from C to D as compared to the distance she walked from A to C.

So,

CB + BD = 2 X AC

[Dharma]

clblinym:

Hi, Can anyone help in solving the following 4 questions.


They are from SMOPS 2004. Thanks in advance!!
http://postimage.org/image/11liujpr8/

Thank you very much.


Regards,
Amy

http://postimage.org/image/2t4uonlj8/

[clblinym]

Dharma:

clblinym:

[quote=\"Dharma\"]Q19


When Betty and David at Pt C, they walked 1/2 the circumference in total. When they meet for the 2nd at Pt D, they walked the circumference in total ( from Pt C to Pt D)

AC = 80m
BD = 60m

2 x AC = CB + BD
CB = 160m - 60m = 100m

Circumference = (60m + 100m) x 2 = 360m

Dear Dhrma,
I still can't figure out how you get
2 x AC = CB + BD. Can you explain? Thanks

Thanks,
Amy

Hi Amy,

Both Betty and David walk at constant speed.
When they meet at Point C, notice that in total both of them covered a distance of 1/2 the circumference of the circle.

Then from Point C to Point, in total both them covered a distance that is equal to the circumference of the circle.

Distance covered by Betty from Point A to Point C when she first met David = AC.

Distance covered by Betty from Point C to Point D when she met David again = CB + BD

Since her walking speed is constant, she had to walk twice the distance from C to D as compared to the distance she walked from A to C.

So,

CB + BD = 2 X AC[/quote]Hi, Dharma
Now I can figure it out.
I really appreciate your kind sharing and patience !!

Regards,
Amy

[john69888]

Dear All,


How to print the JPG file math guru posted on Kiasuparents? I download the jpg files and print the files, but it is NOT clear.

john69888:

Dear All,

How to print the JPG file math guru posted on Kiasuparents? I download the jpg files and print the files, but it is NOT clear.

Pls kindly tell how to print the JPG file math guru posted on Kiasuparents.

Thanks,

Liew

mathsguru:

[quote=\"suiyuan\"]1)During a warehouse book sale, Sally spent 62.5% of her money on 24 books and 18 pens. She also spent 25% of her remaining money on 18 files. Each pen costs 8/9 as much as the price of one book. The file costs $7.80 less than a book. Find the total cost of one book and one pen.

Hi Suiyuan,

Please see my solution and explanation in the attached picture.

http://www.postimage.org/image.php?v=aV1esa5S

Cheers,
MathsGuru

[/quote]

[clblinym]

Dharma:

clblinym:

Hi, Can anyone help in solving the following 4 questions.


They are from SMOPS 2004. Thanks in advance!!
http://postimage.org/image/11liujpr8/

Thank you very much.


Regards,
Amy

http://postimage.org/image/2t4uonlj8/

Hi, Dharma

Thank you very much. Your explanation is easy to understand. I really appreciate your help.

Regards,
Amy

[Dharma]

clblinym:

Hi, Can anyone help in solving the following 4 questions.


They are from SMOPS 2004. Thanks in advance!!
http://postimage.org/image/11lki3290/

Thank you very much.


The answers are
Q19 (360 m)
Q28 (24 cm2)
Q29 (64665912)
Q30 (8, 11, 81) (12,4,84) (4, 18, 78 )


Regards,
Amy

Assume that telephone number is ABCDEFGH
ABC + DEFGH = 66558
ABCDE + FGH = 65577
A = 6
D = 6

60000 + 1000E + 100(6 + F) + 10(B + G) + (C + H) = 66,558
60000 + 1000B + 100(C + F) + 10(6 + G) + (E + H) = 65,577

E is either 6 or 5
B is either 5 or 4
C + H => 8 or 18
E + H => 7 or 17

6 + G = 7. So, G = 1
We know that
C + H = 8 and
E + H = 7

B + G = 5
B = 4
C + F = 15
6 + F = 15
C = 6
F = 9
1+ E = 6
E = 5
C + H = 8
H = 8 – 6 = 2
Tel number = ABCDEFGH = 64665912

[clblinym]

Dharma:

clblinym:

Hi, Can anyone help in solving the following 4 questions.


They are from SMOPS 2004. Thanks in advance!!
http://postimage.org/image/11lki3290/

Thank you very much.


The answers are
Q19 (360 m)
Q28 (24 cm2)
Q29 (64665912)
Q30 (8, 11, 81) (12,4,84) (4, 18, 78 )


Regards,
Amy

Assume that telephone number is ABCDEFGH
ABC + DEFGH = 66558
ABCDE + FGH = 65577
A = 6
D = 6

60000 + 1000E + 100(6 + F) + 10(B + G) + (C + H) = 66,558
60000 + 1000B + 100(C + F) + 10(6 + G) + (E + H) = 65,577

E is either 6 or 5
B is either 5 or 4
C + H => 8 or 18
E + H => 7 or 17

6 + G = 7. So, G = 1
We know that
C + H = 8 and
E + H = 7

B + G = 5
B = 4
C + F = 15
6 + F = 15
C = 6
F = 9
1+ E = 6
E = 5
C + H = 8
H = 8 – 6 = 2
Tel number = ABCDEFGH = 64665912

Hi, Dharma
Thank you for your detailed explanation. Appreciate your help.

Regards,
Amy

[Dharma]

clblinym:

Hi, Can anyone help in solving the following 4 questions.


http://postimage.org/image/11lm5meqs/

Is there any easier or shorter way to solve Q30? Thank you very much.


The answers are
Q19 (360 m)
Q28 (24 cm2)
Q29 (64665912)
Q30 (8, 11, 81) (12,4,84) (4, 18, 78 )


Regards,
Amy

A = Chocolate
B = Cheese
C = Durian

A + B + C = 100
5A + 3B + 1/3C = 100
15A + 9B + C = 300
14A + 8B = 200
7A + 4B = 100

7A + 4B = A + B + C
C = 6A + 3B = 3(2A + B)

3A + 3B + 3C = 300
5A + 3B + 1/3C = 100
8/3C – 2A = 200
2A = 8/3C – 200
A = 4/3C – 100

4/3C > 100
C > 75
Use C = 78
3(2A + B) = 78
2A + B = 26
A + B = 22
A = 26 – 22 = 4
A = 4, B = 18, C = 78
If C = 81,
2A + B = 27
A + B = 19
A = 8
B = 11
A = 8, B = 11 , C = 81
If C = 84,
2A + B = 28
A + B = 16
A = 12
B = 4
A = 12, B = 4, C = 84
If C = 87
2A + B = 29
A + B = 13
A = 16 (Not possible - reject)

If C = 90
2A + B = 30
A + B = 10
A = 20 (Not possible - reject)